Introduction

Abstract

The introduction focuses on the career and work of Santorio Santori. It notes the contrast between his great influence before 1800 and his neglect in subsequent scholarship and offers an explanation of this. It then provides a revised account of his life, drawing on many new archival discoveries (including a new portrait) as well as a close reading of his own publications. It shows the importance of his family’s technical background, and his education and ongoing collective work with the innovative and politically progressive circles of the Morisini family and Paolo Sarpi in Venice, whose influence assisted his career as a physician and then professor at Padua, as well as ensuring his loss of position when more conservative forces triumphed there. The key innovations in each of his publications are explored and explained, showing his consistent commitment to quantification of the body through experimentation based on new instruments, but his positioning of this work within a Galenic framework of medical research and practice. His relationship with Galileo is clarified, confirming Santorio’s independence as both a philosopher and an inventor of instruments such as the pulsilogium and thermometer, and a summary is given of the purposes for which Santorio designed his instruments. The corpuscularian philosophy which underpinned this work is explored in the next chapter.

Anatomists have in effect discovered many elegant things, but the majority seems to be more curious than useful matters, and the origin of diseases should be pursued not so much by hands but by adopting a precise logic, which—except for Santorio amongst the earlier [priores], and Descartes amongst the most recent [novissimi]—I find in very few authors.

—G. W. Leibniz

Leibniz to Herman Conring (Hanover, 24 August 1677) in Gottfried Wilhelm (von) Leibniz, Sämtliche Schriften und Briefe, II.1 (Berlin: Academie Verlag, 2006), 563 (original quote with context): ‘Quid enim est post studium pietatis cura sanitatis utilius. Nam in plerisque rebus nobis consulere possumus mediocri prudentia: at sanitatis conservationem fere casui committere coguntur homines, in tanta verarum causarum ignorantia, quidquid etiam felicitas seculi jactetur. Quanquam enim multa elegantia detexerint Anatomici, pleraque tamen curiosa magis quam utilia videntur, et morborum origines non tam manibus quam accurata ratiocinandi methodo assequi licet. Quam si Sanctorium ex prioribus, Cartesium ex novissimis eximas, in paucis scriptoribus agnosco’ (italics added).

Few, concise remarks, rife with admiration. Leibniz’s words bear witness to the influence that the Italian physician Santorio Santori (1561–1636) exerted on European medicine and natural philosophy. His works introduced quantification in the life sciences, his devices helped Giovanni Alfonso Borelli (1608–1679) to understand the vegetation of plants, Robert Boyle (1627–1691) to conceive his hydrostatic medicine, Giorgio Baglivi (1668–1707) to formulate his doctrine of fluids and solids, and Carl Linnaeus (1707–1778) his dietetics.¹ Santorio’s masterwork, Medicina statica (Venice 1614), became the textbook for generations of physicians and a benchmark of experimental medicine. Praised by Herman Boerhaave (1668–1738) as the ultimate example of medical perfection, it set the groundwork for the studies of Archibald Pitcairne (1652–1713) on fevers, John Floyer (1649–1743) on asthma, James Keill (1673–1719) on digestion, Jean Bernoulli (1667–1748) on nutrition, Jean-Antoine Nollet (1700–1770) on electricity up to Lavoisier’s and Séguin’s researches on oxidation and metabolism.² In learned circles Santorio’s authority was equally heralded to uphold the existence of atoms, to explain action at a distance as a stream of particles (effluvia Sanctorii) and to validate the belief in the resurrection of the dead.³ And yet so pivotal a figure, likened to William Harvey for importance and to Descartes for clarity of method, is today little known, even by the most committed scholars.⁴ While applying to all languages, the lack of studies is particularly conspicuous in the English-speaking world, where the only available monographs are translations of nineteenth-century Italian works, obsolete in their interpretative framework and full of misleading information.

1 A Tale of Oblivion and Rebirth

In part at least, Santorio himself was to blame for conveying such an image of obsolescence. At a quick glance, he might easily pass for the classic Renaissance Paduan physician, busy in providing students with commentaries to the canonical works of Hippocrates, Galen and Avicenna. Santorio himself once joked about the fact that the destiny of commentaries is to fall into oblivion,⁵ a prediction that has so far proved correct. His fame instead rested on his Medicina statica and in particular on its dual emphasis on insensible perspiration and the weighing of the body by using the weighing chair he invented. Although, as we shall see, these inventions rested on his wider corpuscularian philosophy and his experimental methodology, they took on a life of their own, not always necessarily associated with Santorio’s philosophical outlook, and eventually eclipsed the latter. Changes in medicine which appeared to render the medical statics obsolete left Santorio in obscurity, and although recent scholarship—particularly thanks to the contribution of Lucia Dacome⁶—has helped to recover the importance of his statics, such a recovery has not, generally at least, been accompanied by the same interest in Santorio’s output as a whole.

Indeed, the context and content of Santorio’s works seem so at odds with each other that they have been regarded as a trick history played at his expense.⁷ This way of looking at his legacy began in the nineteenth century with Charles Daremberg (1817–1872), to whom Santorio was ‘a more or less forgotten relic of the ancient physiology’:

[…] we cannot share the enthusiasm of Baglivi, Boerhaave and many other 17th- and 18th-century physicians for the medical statics. I do not believe that for this work alone one would erect a marble statue to Sanctorius today, as was done after his death. Sanctorius is more or less forgotten: it is not even read anymore. The whole edifice of his Ars statica is based on the old physiology. […] One would be astonished to find so many ingenious instruments in a commentary which is, moreover, entirely scholastic, if one forgot that Sanctorius was above all a physicist and a mechanic, always in search of novelties; so that medical statics is less the result of a medical system than the application of studies directed towards the work of mechanics proper.⁸

Many have borrowed this interpretation acritically,⁹ though others have more recently delved into Santorio’s works and acknowledged the ground-breaking nature of his ideas.¹⁰ In spite of this, the overall attention devoted to the Venetian physician has hitherto been patchy and very limited in scope. The historiographical reasons for this are not difficult to recount.

Particularly damaging to Santorio’s legacy have been attempts to read his ideas as an embodiment of Galileo’s. The attempt was consistent with a reading of history as a progression towards the final triumph of the scientific method, which had eventually replaced Santorio’s rudimental trials with Lavoisier’s precise chemistry. The life sciences sat at odds with the picture positivists were keen to sketch, and medicine in particular was regarded as an empirical pursuit led by outdated methods and theories. Thus, when the phenomenon of the ‘insensible perspiration’, to which Santorio’s contributions had meanwhile been reduced, ceased to be a pressing concern for medical practice, Santorio was praised instead for having applied Galileo’s methods to medicine.¹¹

Not less problematic, in the least, is the contemporary attempt to counterbalance such an approach. If framing major scientific changes in terms of ‘revolutions’ does get away from Whig history, it sets the discussion of historical problems within a structuralist dichotomy (old/new, before/after, closed/open, etc.), which hinders any attempt to grapple with the complexity of historical sources. Worse still, in a Panglossian move that reduces everything to language and text, it advocates for the necessity of accommodating historical actors and empirical evidence to narratives and historiographic paradigms, thus requiring historians to locate events on the one side or the other of an imaginary threshold, which does not exist. As with all a priori approaches, it works best in challenging established accounts, but it is of little help when—as in this case—the task is that of evaluating the merits of historical figures that have been forgotten or whose contributions defy easy encapsulation. In this sense, the relevance of authors such as Santorio—but the same would apply to Daniel Sennert, as William Newman shows in his contribution—is that they are a constant reminder that there is ‘no simple way’ to deal with history. To approach early modern authors, texts must be studied closely and historical evidence used to enlarge and enrich our tentative characterisations of a period or a trend. Thus, in locating Santorio’s legacy, we pose as reference the existence of a ‘constellation of problems’ that are shaped by both converging and diverging historical accounts, each in turn seen as the result of various actors, ideas, methods and aims admitting of different solutions, where the old and the new survive, commix and react, in a way that is impossible to distil into a unifying picture, be it a paradigm or an episteme.¹² Such an approach will lead to a better understanding of Santorio’s intellectual legacy reversing the oblivion that has affected an author whose contributions are still reduced nowadays to the caricature of a man living on a weighing chair.¹³

This new approach ought to start necessarily from sketching afresh the main traits of Santorio’s life, character and works. These, now enriched by substantial findings, will help us to reconstruct in turn the problems his research was moved by and the directions along which it developed.

2 Santorio’s Life and Works

Sources for Santorio’s life and personality are scarce and the most reliable ones are scattered throughout his works. The hitherto available biographical outlines depend on a patchy reading of Santorio’s works and provide information that is either unreliable or—when it is—depends almost entirely on the biography published in 1750 by the physician Arcadio Capello, who had access to a series of original documents by Santorio’s heirs living in Venice.¹⁴ To the former group belong a series of documents written either as praises of Santorio’s work and inventions or as part of large histories of the University of Padua,¹⁵ while the latter is represented by a variety of nineteenth- as well as twentieth-century contributions.¹⁶ Useful sources to reconstruct Santorio’s intellectual profile can be found in Galileo’s epistolary exchanges with his Venetian colleagues, in the official documents of the University of Padua, in the biographies of Sarpi written by Fulgenzio Micanzio (1570–1654) and Francesco Griselini (1717–1787), as well as in the Iscrizioni Veneziane by Emanuele Antonio Cigogna (1789–1868).¹⁷ Important letters and documents, including Santorio’s last will found in 1883,¹⁸ were published by Modestino del Gaizo (1854–1921)¹⁹ while a few others were discovered around 1960 by Maria Stella Ettari and Marco Procopio, in what has been so far the best monograph on Santorio.²⁰ A substantial number of documents and letters have finally resurfaced as a result of Fabrizio Bigotti’s extensive research into European and American public and private archives, some of which will be used here. In the end, however, the most reliable details and character traits can be found in Santorio’s works. In what follows, we have summarised the available data with the most recent discoveries and reshaped some of the conclusions previously reached by scholars.

2.1 Early Life, Travels and Setting in Venice (1561–1593)

The elder son of Antonio (c. 1520–1592/3) and the noblewoman Elisabetta Cordoni (or Cordonia), Santorio Santori was born in Capodistria—today Koper in Slovenia—on the borders of the Venetian dominion, on 29 March 1561.²¹ He had two sisters, Diana²² and Franceschina, and one brother, Isidoro (d. 1618).²³ The Santori family—also known as Santorio, Santorii or De Sanctoriis, Figs. 1.1 and 1.2—was originally from Spilimbergo in Friuli, where Santorio’s grandfather, Isidoro, was a notary and a teacher at the local schools (1516–1518).²⁴ His son Antonio moved to Capodistria in 1548 when he was appointed ‘bombardier and keeper in chief of munitions’ (bombardiere e sopramassaro delle munizioni) by the Senate of Venice.²⁵ Although the position entailed responsibility mostly in administering munitions, supplying new weapons and instructing young apprentices in the art of artillery, Antonio also managed the proceeds of the local salt pans, which were called ‘old and new Santorio’ (Santorio vecchio e nuovo) as late as the early nineteenth century.²⁶ The Venetian authorities, reacting in part to a complaint from the school of bombardiers in Capodistria, officially reproached Antonio for neglecting his duties in 1583,²⁷ but an agreement was reached and Santorio’s father was subsequently praised for his effort and commitment to his work.²⁸

Fig. 1.1

Santorio’s Coat of Arms as portrayed on the engraving by Jacopo Piccini (1659)

Fig. 1.2

Santorio’s Coat of Arms in the Atrium of Palazzo Belgramoni-Tacco (seventeenth century). Regional Museum, Koper (Capodistria)

Antonio’s knowledge of the practical aspects of mechanics and chemistry related to artillery,²⁹ as well as his profitable management of the family’s business, helped to shape the mind-set of his son, both personally and intellectually. The invention of instruments such as the anemometer, conceived as a maritime tool to use to predict thunderstorms in open sea, and Santorio’s reading of the bodily balance as a system of double bookkeeping (additio et ablatio) may well reflect this influence.³⁰ Furthermore, the family’s long-standing tradition as notaries and lawyers was pivotal in shaping Santorio’s approach to finance, which, by the end of his life, led him to accumulate a very large patrimony of 41,730 ducats, even if we only include the legacies Santorio himself provides in his testament.³¹

His first studies were probably undertaken privately, but due to a long-standing acquaintance between the Santori and Morosini families, in 1574–1578 he was received along with his brother Isidoro into the Morosinis’ house in Venice.³² There he studied with Andrea (1558–1618), Nicolò (1560–1602) and Paolo (1566–1637) Morosini and befriended Nicolò Contarini (1553–1631), the future Doge and one of the prominent members of the Ridotto Morosini. The curriculum in the Morosini family included mathematics, philosophy and classical letters as well as consort music.³³ Santorio himself tells us that in his youth he played brass instruments to expand his thoracic capacity, and it is not difficult imagining him involved in the performance of some of the then popular ricercari and canzoni by Andrea Gabrieli (1533–1585).³⁴ Coinciding approximately with the beginning of Morosini’s political career (1578), Santorio enrolled in the Regio transmarina at the University of Padua, where he studied with Orazio Augenio (1527–1603), Bernardino Paterno (d.1587), Girolamo Mercuriale (1530–1606) and Jacopo Zabarella (1533–1589)³⁵ and where he eventually graduated in philosophy and medicine. The year 1582, often taken as the year of Santorio’s graduation, relies on a false conjecture made by Capello which unfortunately has been taken for granted by all subsequent scholars.³⁶ Lasting seven years, and beginning at approximately 1578, Santorio could only graduate in medicine in 1585.³⁷

Aside from his prominent scientific studies, Santorio cultivated some literary interests. He was a member, and for a short period the president (c. 1586–1587), of the academy known as Academia Palladia or dei Palladii based in Capodistria.³⁸ This was a local gathering of young humanists interested in love poetry, music and classical studies. Santorio distinguished himself amongst the other members as most interested in natural philosophical studies, his name being quoted in relation to a dispute (dubbio quarto) on colours and their psychological effects.³⁹ Another glimpse into the kind of discussion Santorio was involved in during this early period is found in Santorio’s later editing of the Epistole d’Ovidio (1604) by his friend Marc’Antonio Valdera (1567?–1604), a member of the group prematurely deceased.⁴⁰ The interests manifested in the Academia Palladia in Capodistria did not prevent Santorio from entertaining a more fruitful engagement with the Paduan scientific and cultural élite. In 1587–1588 we find him as a member of the circle of scholars and natural philosophers gathering around the humanist Gian Vincenzo Pinelli (1535–1601) where he met and befriended Paolo Sarpi (1558–1621), who played a key role in Santorio’s personal, political and scientific development.⁴¹

By 1587, Santorio was a sufficiently renowned physician to be officially recommended on behalf of the University of Padua (thanks to the intermediation of the bishop Nicolò Galliero, 1528–1595), for a position in Poland at the service of a local prince,⁴² probably in the quality of a military physician.⁴³ This position lasted five years and involved extensive trips also to Hungary and Croatia (Carlovac), allowing Santorio the freedom to occasionally come back to Venice.⁴⁴ The resumé of a letter sent to the judges and majors of Capodistria by their representatives in Venice provides evidence that in 1589 Santorio had departed for Poland but could occasionally travel back. Discussing a list of possible candidates recommended for the position of the local doctor in Capodistria, the representatives state that, while it had been difficult to speak to Santorio due to his being very far away from his homeland (essendo egli stato lontanissimo), they were nonetheless able to meet him a couple of times and that he would have accepted the position for 200 ducats.⁴⁵ From this and Santorio’s testimony, we can infer that the period Santorio spent abroad was approximately 1588–1592/1593. Indeed, as early as 1594 we find him back in Venice, as the recipient of Mercuriale’s consult addressing Santorio’s concerns about the cure of a melancholic disease afflicting the Venetian nobleman Arcangelo Agostino.⁴⁶ In keeping with Capello’s account, scholars have fixed Santorio’s return to Venice at around 1599, but 1594 is much more likely and is further corroborated by the epistolary correspondence between Santorio and the physician Eustachio Rudio (1548–1612). In it Santorio had informed his friend as to the hesitations felt in the Venetian establishment in following up on the promise to appoint Rudio at the chair of practical medicine in Padua, which eventually took place in 1599.⁴⁷

By the early 1590s, Santorio had already developed his distinctive interests in quantification and experimental medicine. If we accept what he states in the preface of his Medicina statica (1614), and later again in his letter to Galileo (1615), he had been experimenting on himself as well as on different subjects for a period of 25–30 years.⁴⁸ This points to 1584 as the earliest date for the beginning of his trials, prior to any possible meeting with Galileo. Santorio’s studies on optics also took shape around that period and he had the opportunity to refine his knowledge of applied mathematics as part of Pinelli’s circle.⁴⁹ Pivotal to his early scientific development were the influences of his teacher Giacomo Zabarella, as well as those of Contarini and Sarpi. While Zabarella’s works introduced Santorio to the purest form of ‘Venetian Aristotelianism’, which stressed logical rigour, method and natural philosophical explanations over more metaphysical and theological commitments typical of the late scholastics, Contarini emphasised the importance of empiricism and scepticism against the use of authorities in philosophical disputes, as exemplified in his De perfectione rerum libri sex (1576). This attitude was later sealed by the personality of Sarpi, to whom Santorio remained deeply attached throughout his life.⁵⁰ In the early 1600s Sarpi managed to enrol Santorio as the physician of the Convent of the Servites in Venice, and given the proximity of Santorio’s house to the convent he was the first to assist Sarpi when he was attacked there by assassins paid by the Roman Curia on 5 October 1607.⁵¹ The two shared a variety of interests, not only in medicine and anatomy, but also in distillation, quantification and optics. A case in point are Sarpi’s early notes on the composition of matter, collected in the Pensieri Naturali as early as 1578, which form the background against which to read Santorio’s approach to the same question in his first work, (1603). Here Santorio pinpoints matter’s most important features—as Sarpi before him—as ‘position’, ‘shape’ and ‘number’ (situs, figura, numerus). The influence was in any case mutual, for it seems that Sarpi later borrowed from Santorio in the making of his Pensieri Medico Morali.⁵²

As someone whom Santorio had grown up with, Andrea Morosini exerted a more intimate influence on him. Animated by a profound sense of devotion to their studies, both men preferred to remain socially inconspicuous. Three years his senior, Morosini was to Santorio a model of moral and political integrity. This was partly due to Morosini’s religious principles—in keeping with which Santorio had been educated—and political attitudes, admittedly more conservative than those of Sarpi or Contarini. Significantly, both men remained unmarried. Yet Santorio’s inclinations towards celibacy were, unlike those of Morosini, of a more ‘practical’ kind. The scorn of romantic relationships, eschewed by Santorio as a form of insanity (species humanae stultitiae, delirii species),⁵³ was the main motivation behind the decision to remain unmarried, which never prevented him from engaging in ‘less committed’ relationships. In fact, to get a clue as to the kind of celibacy Santorio practised, one only needs to read section six of Medicina statica, ‘On coitus’ (De venere), where Santorio reports the results of his self-experiments on the effects of coitus on perspiration. Therein he recommends sexual intercourse (significantly with no mention as to whether it could be practised inside or outside marriage) as a healthy practice leading to a long life. By and large, his approach to the matter was extremely open. In some works, he goes so far as to engage with aspects of pederasty—widespread in the Venetian nobility of the time—which he handles without any apparent moral prejudice.⁵⁴ Santorio’s critics were, of course, scandalised by such an attitude and some later commentators apologised to their readers for how sex was treated so openly in the text.⁵⁵

Morosini, Contarini and Sarpi were to play an instrumental role in shaping Santorio’s career and the political links he forged with the intelligentsia of Venice, first introducing him to the Ridotto Morosini and later leading to his appointment to the first chair of theoretical medicine in Padua (1611).

It is difficult to locate the activity of the Ridotto within a precise timeline. Its nightly gatherings, taking place at Morosini’s house in San Luca over the Grand Canal (today Palazzo Cavalli), lasted approximately from 1578 to 1598. Andrea and Nicolò Morosini gathered around themselves the highest echelons of the Venetian nobility, including the future doges Leonardo Donà (1536–1612) and Nicolò Contarini, Paolo Sarpi and his biographer Fulgenzio Micanzio (1570–1654), the future Bishop of Belluno Alvise (Luigi) Lollino (1552–1625), the mathematicians Francesco Barozzi (1537–1604) and Galileo Galilei (1564–1642), the physicians Alessandro Massaria (1510–1598) and Girolamo Fabrici d’Acquapendente (1533–1619) and, for a brief period in 1592, the philosopher Giordano Bruno (1548–1600).⁵⁶ The themes discussed were diverse, spanning from science to religion and politics. Micanzio and Lollino recall these gatherings as dedicated to ethics and natural philosophy, while being ‘unpretentious and purely directed towards the attainment of truth’.⁵⁷ And yet the activity of the members of the Ridotto must be located also within a culture of secrecy characteristic of the Venetian society of the time, particularly with regards to political matters. Politically, in fact, the majority of the members of the Ridotto belonged to the most progressive party of Venice (the so-called giovani, meaning ‘patricians of recent nobility’) and were linked by strong opposition to Papal and Spanish policies, later to be reflected in their action during the Venetian interdict.⁵⁸

2.2 Between Venice and Padua (1593–1611)

The ten years between Santorio’s return to Venice and the publication of his first work (1603) are wrapped in obscurity. From an intellectual standpoint, the publication of the Methodi vitandorum errorum omnium qui in arte medica contingunt libri XV (Venice 1603) crowns the completion of Santorio’s early studies and medical practice. The work, which Albrecht von Haller (1707–1777) defined as ‘of great importance if little quoted’ (magni momenti opus etsi raro citatur),⁵⁹ is divided into fifteen books, which is reminiscent of the articulation of Galen’s De methodo medendi. Yet the work is not a commentary. Differential diagnosis and post-Vesalian anatomy set the general background against which Santorio defines the principles of a new method to avoid the errors committed by empirical doctors. This method is grounded in logic and in methodologically framed observation which, in order to be certain, must be universal (i.e. general propositions must be convertible in all cases), accidentality and individuality having no share in it.⁶⁰ To reach such certainty Santorio criticises both Galen’s anatomy and those who are blind to his authority, he debunks occult qualities and redefines the rapport between universals and particulars. One of the points in targeting empirical doctors is to show that induction per se does not provide any certainty: if anything, it is prone to logical fallacies and leads to the death of the patients. Individuals, on the other hand, ought not to be seen as qualitative distinct atoms but as temporal and spatial instantiations of universal properties (distinguntur per hinc et nunc) which are the same in all and are hence measurable.⁶¹ Such properties are quantitative, being figure, number and position, and out of them all the perceptual qualities emerge, in a clocklike mechanism.⁶² These premises allow the doctor to gather essential information about the arrangement of universal properties in individual subjects and so to draw a precise diagnosis sustained and mediated by the use of instruments such as the pulsilogium, a pendulum-regulated device that allows one to monitor variations in pulse frequency over time (see Figure 2.6).⁶³ The book gained immediate success and established Santorio as a medical authority well beyond Italy.⁶⁴ Throughout the seventeenth century, it still constituted a source for Joachim Jungius (1587–1657), Caspar Bartholin the Elder (1585–1629) and Gottlieb Wilhelm (von) Leibniz (1646–1716).⁶⁵ Despite this initial success, however, Santorio kept practicing in Venice as a private physician.

The years 1605–1607 saw the development and final settlement of the Venetian interdict, in which Venice defended successfully its liberty against the meddling of the Pope and his nuncii. Although Santorio kept a low profile throughout the unfolding of the political events, in 1610 his name was mentioned by Fulgenzio Manfredi (1560–1610)—a theologian who, initially close to Sarpi, later became an informant of the Roman Curia—as someone who read prohibited books and was acquainted with heretics. From both personal and official accounts we are informed that Santorio indeed was close to Sir Henry Wotton (1568–1639), the English ambassador in Venice, who the Roman Curia monitored closely as an active instigator of Protestant doctrines and smuggler of prohibited books in the Venetian nobility, via the mediation of Paolo Sarpi and his friends.⁶⁶ Manfredi reported Santorio as of close conversation with Sarpi and reveals that both Sarpi and Contarini were plotting to provide him with a chair in medicine at Padua.⁶⁷ And, on 6 October 1611, Santorio was indeed appointed to the chair of theoretical medicine and also became affiliated to the ‘Collegio dei Medici Fisici’ in Venice.⁶⁸ Although important, his political connections were considerably strengthened by the esteem of his colleagues. Amongst them was the Milanese doctor Lodovico Settala (1550–1633) who, when requested by the Senate of Venice to hold the same chair, declined, recommending Santorio as the most worthy candidate.⁶⁹ Santorio and Settala maintained a very close relationship throughout their lives, further strengthened by the arrival in Padua of Settala’s son Senatore (c. 1590–1636) to study medicine with Santorio. In a letter to his father, written in 1613, Senatore provides a first-hand account of Santorio’s performance as a reader. He describes him as a teacher of great value, clear in his exposition, although not provided with as strong a voice in enunciation as his colleagues, by whom in any case he was little loved, due to his many medical innovations and inventions.⁷⁰

Santorio’s first work as a professor of theoretical medicine was the Commentaria in Artem medicinalem Galeni libri tres (Venice 1612, completed in 1611). Although it has so far attracted attention because of the passages in which Santorio describes the thermometer, this lengthy work (altogether more than 600 large folios) is relevant in its own right as it adds substantial new elements to Santorio’s physiological and physical theories, experiments and observations as well as new details on his life and his encounters.

2.3 The Ars de Statica Medicina and the Obizzi Controversy (1614–1615)

Two years later, Santorio came to prominence as an international authority with the publication of his masterwork, the Ars de statica medicina (Venice 1614). This little book, dedicated to Nicolò Contarini, consisted of a series of aphorisms divided into seven sections. The first section introduces the general criteria to measure the insensible perspiration of the body (de ponderatione insensibilis perspirationis) and is followed by the other six, arranged according to the order of the six non-naturals (sex res non naturales), being those factors like air, exercise, sleeping and waking, food and drink, excretion, sex and the passions of the soul, which the human subject was believed to be in control of. At an initial stage, Santorio had thought to write a commentary to the statics, possibly to explain how he gained his results, but he soon realised that it was superfluous.⁷¹ Given the familiarity of physicians with Hippocrates’ aphorisms as well as the logical proximity of these latter to mathematical axioms, Santorio deemed the work clear enough to be published in octavo. Besides, commentaries to the work started circulating independently of Santorio’s knowledge or will.⁷² As he declared in a letter to Galileo dated 1615, anyone interested in the new method would be able to appreciate its rigour by engaging in the daily experimentations that the book describes and thus appreciate aphorisms as the best literary form to collect and record them. In other words, while the necessary explanation of the method is supposed to come from experimentation, its general outline remains accessible—because of its clarity—to anyone interested in it. Beyond their adherence to intrinsic experimental needs, aphorisms are meant to be memorable, all the while inviting others to expand upon the knowledge enclosed in the short sentences—a strategy undoubtedly meant also to enlarge the repute of Santorio as a medical authority. Although Santorio does not supply enough details as to the conditions of his experiments, we know that in experimenting on himself he was assisted by fellow physician Girolamo Tebaldi da Oderzo (1575–1641), who was as keen as Santorio on the application of the new method.⁷³ Santorio performed his experiments on other subjects as well, by using a special weighing chair, later engraved as part of his Commentaries on Avicenna’s Canon (1625) and included in the subsequent editions of the Medicina statica (Figs. 1.3 and 1.4)

Fig. 1.3

Santorio in his weighing chair. From Santorio 1625, col. 781

Fig. 1.4

Ideal portrait of Santorio as sitting on his chair. Letterhead from Stephan Mack, Scriptores Medico-Statici, Ms 11100, p. 159, Österreichische Nationalbibliothek, Vienna

According to its author, Medicina statica serves three different purposes: the first is diagnostic, allowing one to foresee the onset of diseases through variations in body weight; the second is dietetic, focusing on rationalisation of regimen; while the last is the prolongation of life.⁷⁴ All three targets are grounded in Santorio’s experimental proof that the bodily equilibrium between ingested food and the sensible excretions is regulated by the dispersion of an insensible matter (perspiratio insensibilis) whose quantitative variations determine a state of health or disease in each individual.⁷⁵ The hypothesis on which the experiments are based is that, in normal conditions, the body tends to maintain the same weight.⁷⁶ As a consequence, the dispersion of a regular quantity of matter points to a healthy constitution, whilst sudden changes—all other parameters being invariant—reveal the onset of a latent disease.⁷⁷ Latent and insensible are important terms to Santorio as his statics aims at extending the perception of the doctor, making ‘apparent’ what is latent and ‘sensible’ what is insensible.⁷⁸ Thus, the quantitative measurement of the perspiratio insensibilis is intended less as a matter of investigation per se than as an indication of the present and future conditions of the body, with more minute calculations meant to sketch a reliable trend in the patient’s health.⁷⁹ By calculating the peak of perspiration the doctor could measure the quantity of drugs to be administered at any given stage of the disease progression, while ascertaining the magnitude of it (magnitudo morbi).⁸⁰ In an age when the only possible non-invasive medical interventions were diet, bloodletting and purging Santorio’s statics sparked a revolution: it showed that the most fundamental processes by means of which the organism preserves itself are quantitative and must accordingly be analysed experimentally, rather than theoretically.⁸¹ In this sense, the fundamental change in modern medicine brought about by Medicina statica was to convert the classical concept of equilibrium, as ideal as subjective, into a statical problem of balance between fluids and solids of the body, the effects of which could be tested and thus controlled. The work, however, was also meant to serve patients, insofar as the latter could use the statical measurements to obtain a median calculation of how much they needed to eat and drink per day, thus leading to the prolongation of life.

The prevailing focus on metabolism has led many scholars to interpret Medicina statica as a work concerned with problems and belonging to the framework of traditional medicine. Its emphasis on humours and diet can be certainly construed as in line with this interpretation, but a closer look shows that the conceptual structure underpinning Santorio’s work has indeed changed. For while it is true that in ancient and mediaeval physics all natural transformations were conceived as either cooking processes or digestions (πέψις, concoctio, digestio, assimilatio), it is equally clear that medical statics presupposes a different meaning of digestion. This consists now of two acts, the ‘distillation’ (elixatio), which brings about the separation of humours into their elemental components, and the complementary act of ‘dispersion’ (evacuatio) of residues in form of perspirable matter.⁸² It is therefore entirely relevant to Santorio’s conception that he does not list the actions of ‘emptying’ and ‘filling’ the body (inantio et repletio) within the six non-naturals: these are not parameters to be measured but the very actions by means of which the body keeps its balance, a balance that is conceived quantitatively as regulated by mechanical actions.

In any case, but from a modern standpoint, there cannot be any doubt that Santorio, like many other men of the period, overestimated the applications of his discovery. Then as now, weight is only one out of the many parameters that are to be taken into account when sketching a reliable diagnosis. Nor is it true that diseases are first ‘introduced’ into the body by a weight change.⁸³ What’s more, the very idea that all gains and losses in bodily weight should be compensated by an equivalent evacuation or addition lent itself to easy simplification, as happened in the seventeenth century when the use of diaphoretics became a kind of panacea, curing everything from fevers to asthma, up to epidemic diseases.⁸⁴ This was probably less Santorio’s defect than his followers’: Santorio regarded his Medicina statica as an ‘art’ and an ‘instrument’ which could assist medical practice not replace it with a priori deductions. Furthermore, it is a great loss that Santorio never published the tabulated data of his experiments, which could have provided vital insights into his method. In keeping with Obizzi’s criticisms, Kurt Sprengel had already pinpointed this as a fundamental fault of Santorio’s method.⁸⁵ To be sure, however, it was the standard modus operandi of his time: Galileo, Beeckman and Kepler constitute an exception only because we possess their manuscripts to supplement their published writings.

Despite the defects, of which later generations became more critical, the relevance of the Medicina statica in the history of medicine and science is difficult to overestimate, as the essays in this volume demonstrate. Santorio’s work established the principle that in all natural bodies qualitative changes are constantly and necessarily associated with quantitative ones.⁸⁶ Given the role the human body still played in the understanding of the natural world at the beginning of the seventeenth century, Medicina statica had a major impact on the making of experimental sciences, especially in early modern chemistry, where it helped establish the principle of the conservation of matter.

If appreciated by many, the ground-breaking novelty of the work inevitably attracted criticisms, initially in a pamphlet articulated in three dialogues titled Staticomastix, sive staticae medicinae demolitio (Ferrara 1615), written by Ippolito Obizzi (c. 1550–after 1634). Obizzi uses ad hominem arguments to minimise the importance of Medicina statica, but at times he raises interesting objections,⁸⁷ notably that Santorio’s statics does not take into account the causes and qualities of perspiration, thus making the quantitative analysis irrelevant as a parameter. Obizzi argues that the same quantity of perspiration can be obtained either by natural means (secundum naturam) or by unnatural means (praeter naturam), and that this difference cannot be detected by adopting Santorio’s methods.⁸⁸ Obizzi also reproaches Santorio for not taking into due account the nature of individuals he measures. These become standardised subjects whose age, gender and conditions Santorio does not declare.⁸⁹ Obizzi is especially sceptical of Santorio’s meticulous calculations in terms of ounces and scruples, which he finds impossible to measure. On a personal level, Obizzi criticises Santorio’s open stance towards sex, which he finds impious and not suitable to priests, monks and other celibates.⁹⁰

It took some time for Santorio to reply properly to these attacks. He indirectly did so in 1612—replying to the criticisms an unknown physician had voiced amongst common friends—and again in 1625, while finally coming out publicly against Obizzi in 1634, with his Responsio ad Staticomasticen consisting of seventeen aphorisms added as an eighth section to Medicina statica, thereafter included in almost all editions of the work.⁹¹ Santorio’s responsiones are concise but sharp: Obizzi is an astrologer who has no grasp of experimental method and condemns others’ results on the grounds of hypotheses that have no experimental backing.⁹² All his criticisms are due to the fact that he does not acknowledge the difference Santorio constantly makes between ‘feeling lighter’ (ad sensum) and ‘being lighter’ according to the measurement of the scale (ad stateram).⁹³ In fact Santorio had recognised the difference in the quality and nature of perspiration, but had conceived both as measurable. In order to assess such difference he had invented instruments and devised experiments that were unknown to Galen or any of the ancients.⁹⁴ This latter point helps us to understand another essential principle that Medicina statica introduced into European medicine, namely the distinction between ‘perceived’ (ad sensum) and ‘measured’ (ad stateram) reality. The distinction resurfaced again in the correspondence of John Locke (1632–1704), where it was used by Nicolas Toinard (1628–1706) as an early version of the famous distinction between primary and secondary qualities.⁹⁵

2.4 President of the Collegio Veneto and Resignation from the Chair of Medicine (1616–1624)

The academic years following the Obizzi controversy ran smoothly and Santorio enjoyed the gratitude and affection of his students. In the period 1616–1618 and again from 1622 to 1624, he was appointed as the president of the Collegio Veneto.⁹⁶ The Collegio was created in 1616 and advertised externally as an institution to grant poor students at Padua the opportunity to obtain a doctoral degree without sustaining the steep prices of the official procedure, but it also acted as an instrument of the Republic to allow Protestant students to bypass the papal imposition that compelled official students at Padua to profess publicly their Roman Catholic faith. Another aim was to abolish the arbitrariness of the Conti Palatini, who were previously given the authority to bestow doctorates privatim without requesting permission from the University of Padua or the Senate.⁹⁷ Those granted by the Collegio were prestigious and highly sought, as Santorio became internationally famous. Around 1614–1616, possibly marking the event of Santorio’s appointment as the first chairman of the Collegio, he had his portrait made (Fig. 1.5). This portrait has been identified as Santorio in 2017 by Fabrizio Bigotti, for reasons of its close resemblance to the known engraving by Jacopo Piccini (Fig. 1.6), the height of the sitter, compatibility of the profile with the engraving of Santorio in his chair (1625) and the surviving skull kept in Padua, as well as important details showed by the burial at the Ateneo Veneto (such as beard and overcoat) (Fig. 1.7), as well as for the size of the little book in octavo, which is precisely the size of the Medicina statica.⁹⁸ Although the portrait features no marks or inscriptions, the man may be easily described as an academic whose age is also compatible with that of Santorio (who was 55 years old in 1616) while the painter, anonymous but conjecturally identified as Frans Pourbus II (1569–1622), has been previously described as a north-Italian painter, thus making the identification with Santorio’s portraitist very likely. The later painting (whereabouts unknown), engraved by Piccini in 1659, was probably made by Tiberio Tinelli (1586–1639).⁹⁹

Fig. 1.5

Anonymous (Frans Pourbus II?) Portrait of Santorio Santori. (Identified by Fabrizio Bigotti in 2017). Oil on panel, 91 x 76. Antwerp, The Phoebus Foundation. © The Phoebus Foundation 2020

Fig. 1.6

Santorio Santori engraved by Jacopo Piccini in 1659. From Santorio 1660

Fig. 1.7

Santorio’s burial at the Ateneo Veneto in Venice (originally from the cloister of the Convento dei Serviti). From Paola Rossi, ‘La memoria funebre di Santorio Santorio’, Venezia Arti, 17–18 (2003–2004), 51–56

In any case, around this period Santorio’s name became so important that it led to forgeries of Paduan diplomas, such as a diploma now held at the Royal College of Physicians in London, where an unknown physician has altered the name and date of the diploma to make it seem that he had graduated in Padua with Santorio in 1628, when the Venetian physician had already left his position at least four years earlier.¹⁰⁰

In his capacity as the president of the Collegio, however, Santorio faced the criticisms of the Papal nuncio Berlingero Gessi (1563–1639), who targeted Santorio for his intransigence in following the Senate’s decrees thus bestowing academic degrees in medicine and law on Protestants, Jews, Greeks and many other non-Catholics.¹⁰¹ It became clear to the nuncio that Santorio was acting as Sarpi’s and Contarini’s agent and that he was not easily intimidated.¹⁰² Meanwhile, criticisms came also from the University of Padua: Santorio had in fact misinterpreted the duties associated with his new position in bestowing the doctorate on some students without requesting permission from the University.¹⁰³ The documents of the Acta Nationis Germanicae kept in Padua yield a picture of Santorio as a man drunk with power and confident in the strength of his political connections, making public displays of rage against those who have been awarded doctorates by the University in his absence.¹⁰⁴ But this view should be taken with a grain of salt, not least because Santorio was summoned a second time to the same role in 1622–1624 and the students of the Natio Germanica always manifested their sincerest support and admiration for him. In 1623 he was also accused of negligence in lecturing his students, but he was then fully and promptly exonerated.¹⁰⁵ The accusations were in fact levelled for political purposes. The conflict with the Papal nuncio and the progressive loss of political connections brought Santorio increasingly out of favour with Venice’s political establishment, which started seeing him as a leftover of an outdated party and a hindrance to new conservative politics as the Senate started taking a more conciliatory approach towards the Pope and Spain. Thus, following the death of his friends Agostino da Mula (26 October 1621) and above all of Paolo Sarpi (15 January 1623), Santorio was denied the increase of salary he had demanded for the renewal of his appointment (to be raised from 1200 to 1500 florins) and accordingly resigned in 1624.¹⁰⁶ This was a deliberate decision reflecting the Senate’s changed political attitude to the Collegio Veneto, and to him in particular.¹⁰⁷ The political intent behind the decision became clear with the immediate replacement of Santorio with the Pope’s physician Pompeo Caimo (1568–1631).¹⁰⁸ By 1625, Santorio was civiliter mortuus, having lost all academic privileges and honours.¹⁰⁹ However, the Senate granted Santorio his full salary for that year and a tax reduction—though not an annuity, as wrongly reported in all previous accounts.¹¹⁰ Santorio kept practising privately as a doctor in Venice. Following his resignation, he was offered positions in Bologna, Messina and Pavia, which he refused to continue living in Venice.

One year after his resignation, Santorio published the Commentaria in primam Fen primi libri Canonis Avicennae (1625). The work, begun in 1623, is a collection of his lecture notes and displays for the first time a good number of Santorio’s instruments.¹¹¹ Haller called the work memorabile opus, and indeed it represents the pinnacle of Santorio’s scientific and experimental achievement.¹¹² Writing to his former student Senatore Settala on 27 December 1625, Santorio defines the work as plenty of ‘new thoughts yet grounded on the authority of Hippocrates and Galen’.¹¹³ The book not only shows engravings of various types of pulsilogia, thermometers, hygrometers and the weighing chair, but also instruments for tracheostomy and paracentesis, for palliative care as well as for optical experiments. As seen, these latter had been a long-standing interest for Santorio and we gather from his testament that a manuscript with ‘A hundred problems of physiological optics’ (Cento problemi di ottica fisiologica) was to be handed over to his colleague and friend Girolamo Tebaldi da Oderzo.¹¹⁴ The Commentaries on Avicenna’s Canon had a second reprint in 1626 which is very rare, but some copies present textual variations.¹¹⁵ In one of these, kept in Padua, Santorio informs the reader about the structure of the forthcoming book on ‘Medical instruments no longer seen’ (De instrumentis medicis non amplius visis) that he planned to publish: a book showcasing large engravings with the construction of the new instruments and the ways to use them, most likely similar to the anatomical plates of his colleagues Girolamo Fabrici d’Acquapendente (1533–1619) and Giulio Casserio (1552–1616), with the engravings marked by letter on the one side of the plate followed by explanations on the back of it: a very expensive book both to print and to buy. As we shall see below, Santorio was looking for a patron who could help him to cover these expenses; he thought he had finally found one in Francesco Maria II Della Rovere (1549–1631) to whom he dedicated his last work in 1629.

2.5 The Final Years 1625–1636

With the exception of the Methodi vitandorum errorum...libri XV and the Medicina statica, Santorio’s works were aimed at providing medical students with reliable textbooks. In 1629 he published the last of such textbooks, the Commentaria in primam sectionem Aphorismorum Hippocratis and the little book De remediorum inventione. From 1630 to 1634 Santorio devoted his endeavours to the reprint of previous published works. If actually undertaken, the intended publication of the book De instrumentis medicis was probably frustrated again by the death of Della Rovere in 1631. Furthermore, in 1630 plague broke out in Venice and Santorio was requested by the Senate to give his opinion on the nature of the epidemics. Much speculation has been devoted to why Santorio denied the true nature of the disease. As documented in the essay by Vivian Nutton and Silvana D’Alessio, the nineteenth-century historian Paolo Dolfin ascribed Santorio’s refusal to acknowledge the plague to his political connections with the Senate and to the extraordinary pressure he was under not to compel the authorities to shut down ports and the commercial activities of the city.¹¹⁶ If so, Santorio’s decision would be somewhat mitigated by circumstantial considerations. Doctors were inclined to deny that sporadic epidemics could be identified as plague, not least as such calls were made regularly every year.¹¹⁷ But it seems unlikely that pressure from the Venetian authorities could compel Santorio’s judgement: Santorio was one of the few (and, according to certain testimonies, at some moments the only one) to openly deny that the epidemic disease was indeed a plague.¹¹⁸ If his aim had been to shield his reputation from the possible reaction of the Senate, Santorio would have done better to join the majority party. In any case, throughout the spread of the plague Santorio remained in Venice, helping the authorities to fight its spread and actively assisting the poor of the city by organising the shifts of the corpse carriers.¹¹⁹ In 1634 the advice that he had given and tested personally in fighting the plague was added to the first section of the Medicina statica: Santorio argues that plague is spread by an exhalation (halitus) and that all traditional remedies are vain, with the only effective precautions being either fleeing away or segregating those with the plague.¹²⁰

Santorio spent his final years with his nephew Antonio (1600–1642), who became a physician in Venice on 16 October 1631,¹²¹ and to whom he entrusted his final will, a task Antonio could fulfil only in part, for he died prematurely six years later. Santorio died in Venice on 25 (not 22 as many biographies have it) February 1636 in a house belonging to the Dardani family at the Fondamenta della Sensa over the homonymous canal.¹²² According to the official medical report he died from a urine disease (mal d’orina), but other accounts state that he remained many hours with very feeble or no pulse.¹²³ His remains were buried in a tomb in the cloisters of the church Santa Maria dei Servi, the church of the Servite convent wherein Santorio had served for many years as a physician and confidante of Sarpi. Santorio’s bust, originally placed over the tomb, was removed from the church in 1815 following its partial demolition and is now kept at the Ateneo Veneto in Venice (Fig. 1.7). At the beginning of the nineteenth century, following the destruction of the Chiesa dei Servi, his bones were exhumed by the physician Francesco Aglietti (1757–1836) and Santorio’s skull is now kept at Museum of the History of Medicine (MUSME) in Padua.¹²⁴

The substantial fortune made by Santorio provided his descendants with the opportunity to become permanent citizens of the Republic of Venice (cittadini originari) in 1658,¹²⁵ and to acquire a large villa over the river Brenta, rebuilt in the nineteenth century as Villa Elvira, along with a palazzo in Venice at the Fondamenta Santorio at San Basegio, which was demolished at the end of the eighteenth century.¹²⁶ Santorio also left a considerable amount of money to the ‘Collegio dei Medici Fisici’ in Venice to give an annual Sanctorian Lecture, a practice that began with Santorio’s colleague Girolamo Tebaldi, followed by Giacomo Grandi, Arcadio Capello—his most reliable biographer—and Nicolò Pollaroli and lasted for almost 150 years, up to 1774.¹²⁷

3 ‘Not that Close’: The Problematic Relations Between Santorio and Galileo

We have previously hinted to the relations between Santorio and Galileo, the nature of which has remained a puzzle to historians.¹²⁸ While the two knew each other personally, there was a certain distance between them, both in terms of ideals and characters. In fact, although Santorio and Galileo had similar interests and upbringing, the same friends, and even worked and lived for a while in the same places, neither ever mentions the other directly, not even when they would have had compelling reasons to do so.

In 1623 Galileo writes the Assayer (Il Saggiatore), and in a passage where he introduces his corpuscularian ideas, reference is made to the insensible perspiration of the body (insensibile perpiratione) as an example of the effluvium of corpuscles.¹²⁹ At the time Santorio was the unquestioned authority on this but his name is never mentioned. Santorio reciprocated this tacit dismissal, in 1625, and again in 1629, when he offered his students and readers a consideration of the merits and problems of the Copernican theory.¹³⁰ Unlike others in Padua, Santorio takes the theory seriously and defends it against detractors and superficial objections, none of which prevents him from eventually dismissing Copernicanism on the grounds of observations made with the telescope. One of which is that, if the upholders of the Copernican theory are right in assuming that there is no difference between the terrestrial atmosphere and the skies, then we should expect to witness on the moon an atmosphere similar to the terrestrial one, with corresponding atmospheric events such as rain and winds as well as modification of the soil as due to these environmental factors. But Santorio argues that, looking at the moon ‘with the lens recently invented’ (cum specillo nuper invento), this is not the case.¹³¹ Galileo’s spectre lurks around the entire discussion, but neither his name nor his inventions are ever mentioned. Another episode is that known to Galileo’s scholars as the ‘episode of the notomista’. It was recounted by Santorio in 1603 and then Galileo reworked it slightly, some 30 years later (1632).¹³² To deride those who are addicted to the authority of the ancients, Santorio tells us of a public anatomy where an important Aristotelian scholar of the time had denied that the veins originate from the liver and that the heart is surrounded by a fat substance (pinguedo cordis), thus preferring to blindly follow Aristotle’s authority than his own senses. Galileo ascribed the occasion of the quarrel to the origin of the nerves, but the conclusions are the same as Santorio’s. If the famous episode took place in Santorio’s house—as is likely, due to the fact that he recounts it in the first person—it is interesting that Galileo does not quote him or his source.¹³³

The safest conclusion these series of omissions would suggest is that the two were not close enough to feel comfortable in mentioning each other’s names in published works. Unfortunately, there is more and it involves a question of priority in the invention of two instruments: the pulsilogium and the thermometer.

As seen, the Ridotto Morosini brought Galileo, appointed to the chair of mathematics at Padua in 1592, in close contact with Santorio and Sarpi although other occasions might have occurred earlier at the Pinelli’s circle.¹³⁴ Instruments such as the pulsilogium, known as the earliest applications of the pendulum to medical practice, probably were conceived at these times if not in these meetings. Others, like the thermometer, were realised much later (c. 1610). On the grounds of such a continuity, scholars have often claimed that Santorio simply appropriated Galileo’s inventions. We shall address the merits of such a claim in the next section but it is important to highlight that the claim originated with Galileo himself, who had reclaimed both inventions through the account of his student and biographer Vincenzo Viviani (1622–1703) and in a letter now lost to Giovanni Francesco Sagredo (1571–1620).¹³⁵ Scholars have recently come to doubt many of Galileo’s statements about the priority of his discoveries,¹³⁶ and new documents show that the pulsilogium was already known to the Paduan colleagues of Galileo as an invention of Santorio before Galileo first described his experiments with the pendulum to the mathematician Guidobaldo del Monte in 1602.¹³⁷ This would help explain why, while in Padua and Venice, Galileo never raised any question of priority as to the invention of such an instrument.

The thermometer was somewhat different and a more serious affair, in that it set the tone for much of the subsequent relations between the two. In this case, Galileo seemed to have claimed the priority of the invention immediately, if privately, to Sagredo.

The affair itself was a bit bizarre. Santorio—who must have made his instrument somewhere around 1610¹³⁸—only claimed to have adapted to medical practice an instrument invented by Heron of Alexandria (c. 10–70 A.D.).¹³⁹ Galileo, on the other hand, never mentioned nor used the instrument in any of his experiments.¹⁴⁰ Santorio instead had used the thermometer for medical practice and showed it publicly to his students and colleagues in Padua since 1611, including his friend Agostino da Mula.¹⁴¹ Da Mula came to visit Santorio on 30 June 1612 and told Sagredo about the thermometer.¹⁴² The latter, in turn, reported the news to Galileo. Although Galileo’s reply has not survived it is clear from what Sagredo says in his letter that Galileo claimed the invention. However, it seems that Sagredo himself later became wary of Galileo’s claim. He had invited Galileo to send details and sketches of his thermometers, which Sagredo believed to be more advanced than the ones he had been able to make in the meantime after the indications provided by da Mula. Yet, Galileo never sent any details and Sagredo turned for directions to Santorio who, at this point, refused to give any.¹⁴³ It is against this backdrop that we ought to frame the only surviving document of the Santorio-Galileo relationship: a letter sent by Santorio dated 9 February 1615 (Figs. 1.8–1.10). As it has never been translated into English, it is worth summing up its content, however briefly.

Fig. 1.8

Santorio’s autograph Letter to Galileo—9 February 1615; MS Gal 89, c. 239r, National Library of Florence

Fig. 1.9

Santorio’s autograph Letter to Galileo—9 February 1615; MS Gal 89, c. 239v, National Library of Florence

Fig. 1.10

Santorio’s autograph Letter to Galileo—9 February 1615; MS Gal 89, c. 240r, National Library of Florence

The letter is meant to accompany a copy of Santorio’s Medicina statica, published one year earlier (1614). Apologising for the delay in sending the copy of the work, apparently due to the bookseller who had forgotten to send it, Santorio dwells upon the principles and importance of his research. The work is organised in aphorisms and it hinges on a principle of Hippocrates (medicina est additio et ablatio) but the rest is grounded in Santorio’s experimental trials. After expounding on the importance of the results he had obtained, Santorio defends that he has no need to bother Galileo with providing further details, for his ‘admirable ingenuity’ (ammirabile ingegno) and the daily practice he will make according to the prescriptions of the text, will allow Galileo to understand them for himself. This otherwise usual exchange ends with Santorio stating that he had already shared the secrets (secreti) of the Medicina statica with Galileo’s friends, most notably with Sarpi, Sagredo, Barozzi and da Mula. They all are well acquainted with Santorio’s experiments which spanned 25 years and involved more than 10,000 experimental subjects, amongst which was Galileo himself. Looking at the way it was written, as an addition on the left-hand margin of the letter, and especially the abrupt change of tone, Santorio’s last sentence can be construed as a warning to Galileo, a kind of ‘And, by the way, be aware that’.¹⁴⁴

The elements that are worthy of special attention in this letter are three. First, the detailed explanation provided by Santorio regarding the principles and implications of the Medicina statica suggests that these were relatively unknown to Galileo and thus that work did not depend in any substantial way on the latter’s findings. A second element Santorio highlights is that, unlike the recipient of the letter, their mutual friends in Venice were all acquainted with the details (secreti) of Santorio’s research programme. The most important element, however, is the final one. By emphasising the number of years throughout which experimentation was carried out and by detailing the number of subjects involved in it, which included Galileo, Santorio seems to be warning Galileo that he cannot claim priority on any part of the work, which contained direct reference to the invention of instruments such as the thermometer and the hygrometer.¹⁴⁵

Galileo’s friends in Venice were all aware that Galileo—to use the words of the merchant Fugger—was ‘like the raven of Aesop, which likes to take pride of others’ inventions’.¹⁴⁶ In the aftermath of the discovery of the Medicean planets (1610), da Mula complained that Galileo was boasting about da Mula’s inventions and discoveries, and Sarpi himself played down the prominence of Galileo’s invention and experiments with the telescope, an interest which—as seen—was shared by Santorio.¹⁴⁷ Seen through this lens, one feels compelled to subscribe to the conclusions reached by Alistair Crombie on the matter:

Galileo habitually made claims unsupported by any known evidence and frequently refuted by it. When he heard of a discovery or contribution to science he would claim that he had made it himself, even many years before, as with Santorio’s thermometer (Opere, xi, 350, 506), and Bonaventura Cavalieri’s demonstration of the parabolic trajectory of a projectile (xiv, 386). Sometimes he would appropriate the work without acknowledgment, as perhaps with Francois Viete’s treatise on mechanics (…) and with Mersenne’s formulation of the law relating the frequency of a pendulum to its length (…). He would use every rhetorical device to misrepresent the scientific competence and arguments of opponents, as he did with the Jesuit mathematician and astronomer Orazio Grassi in their dispute over comets, while obstinately rushing himself into some wrong headed and untenable conclusion. He was capable of ignoring almost completely fundamental contemporary theoretical and experimental discoveries, as he did with Kepler’s astronomy and optics.¹⁴⁸

While his friends knew that Galileo’s borrowings were always elaborated on a personal base and eventually came out in writings in a much better shape, this was clearly not the case with the thermometer—whose use Galileo never fully appreciated—neither with the pulsilogium.¹⁴⁹ As we shall see, there are other motivations than the simply contextual ones to argue for Santorio’s full authorship of these and other instruments.

Whatever the true nature of the Santorio-Galileo relationship was, resentment never prevented Santorio, or for that matter Sarpi and others in his Venetian circle, from professing the sincerest admiration for Galileo’s achievements. Altogether, Santorio and Galileo had in common an inquiring mind and a strong sense of independence. Whereas they both were keen to liberate the academic curriculum from the tight spots of scholastic philosophy, they did so in different ways. Galileo was the revolutionary type, brilliant and intransigent, ideological and opportunistic, a courtier at times and a man of spirit. Santorio was instead a patrician, reserved and not inclined to direct polemics: each criticism he levels either at Galen or at Aristotle is always pondered with great care and against a precise target. The overthrow of medicine as a whole was of no appeal to him although—as the Obizzi controversy reveals—it was clear to those who understood the essence of Santorio’s methods that these had the capacity to revolutionise it. As characters, therefore, Galileo and Santorio were squarely opposed. Galileo practised astrology keenly, while Santorio held astrologers as nothing but quacks, seeking to disprove their assumptions once and for all in theory and experiments.¹⁵⁰ The difference in economic means contributed to emphasise such differences. Galileo was paid little and at times had to rely on the generosity of patrons and friends to fund his research. Santorio, who forged links of incredible strength with the Venetian nobility, could also rely on his personal earnings as a physician in Venice, which made him an extraordinarily wealthy man. Despite this, they both fell victims of a political ostracism which compelled Bishop Alessandro Bichi in 1636 to state:

[T]he Venetians are terrible and don't care about anyone, having treated Mercuriale, Galilei, and Santorio even worse in the past, all of whom they left in desperation […].¹⁵¹

4 New Instruments for a New Medicine

With this proviso in mind we can finally address the context and problems posed by Santorio’s instruments. Of the approximately thirty devices that Santorio invented, we can distinguish three general types, namely:

• 1. Instruments for quantification in medicine and natural philosophy (pulsilogia, thermometers, weighing chair, hygrometers, wind and water gauges);

• 2. Instruments intended to help clinical practice (portable bath, suspended and equipped bed, ice bag, dripping pot, humidifier, pneumatic cupping, quenching ball);

• 3. Instruments to be used in surgery (trochar, needle for paracentesis, device to stop bleeding from the nostrils, device to pull out objects accidentally falling in the ear).

For reason of economy of time and space we will be dealing here with the first group only, which can be understood as part of Santorio’s programme of quantification in medicine. He conceived this programme as the measurement of the intensity of a phenomenon in terms of degree.

The starting point of Santorio’s analysis is the recognition that a healthy organism maintains the same parameters unaltered throughout time (homeostasis), unless the process is hindered by the onset of some diseases. This prerequisite (or praecognitum, in the Aristotelian language of the time)¹⁵² is used to define the disease as a distance from the region of normality (morbus est recessus).¹⁵³ In keeping with this insight, Santorio’s instruments are meant to provide a measure of such a distance (varios dimetimur recessus) and he considers them as devices that extend the perception of the physician beyond his usual limits by allowing him to spatially visualise the difference between normal and pathological conditions as well as necessary aids in order to avoid errors in diagnosis. They allowed Santorio to quantify the activity of the body in relation to its weight change, temperature, pulse and environmental conditions such as the temperature, humidity and atmospheric pressure of the air.

Though the applications are ground-breaking, the principle inspiring Santorio is ultimately a reworking of the Galenic rationale, which applied ‘a range’ (latitudo) to health and sickness on the basis of their duration over time (latitudo sanitatis, neutralitatis, morbi). Santorio is willing to acknowledge his debt to Galen and he considers his instruments as outcomes of such an idea, with Medicina statica itself seen as an ‘instrument’ able to confirm, a posteriori, the validity of Galen’s insight:

Galen […] teaches us how we can measure the quantity and strength of hot and cold in intemperate mixtures. He states that the quantity or the strength of the intemperate mixture will be as much as its distance from the natural state (quantus est recessus a statu naturali) […]. I make use of four instruments by means of which I ascertain the quantity of this distance (de quantitate recessus). The first one is an instrument that I invented and is called a pulsilogium, through which we grasp how much in each day each individual departs (recedat) from their best condition. The same result is provided by the second instrument, by means of which, by putting in movement a leaden ball attached to a suspended thread and, from its movement on the thread, and from the greater or smaller lengthening, anyone will be able to observe the natural motion of the pulse and its distance from the natural condition (recessum a naturali). By means of the pulsilogium I measure with great diligence the motion and rest of the artery and I can also compare this measure with the pulse of the previous days. With the third instrument I measure, by means of statical experiments, the various distances (varios recessus) in respect to the natural state. It is not useful to give here further information on the secrets of statics, as in a short time I will publish four hundred aphorisms on statical experiments [i.e. medicina statica]; the fourth instrument, which is wonderfully advantageous, is a sort of glass ampulla, with which we can measure (metiri) not only the temperament of the air, but also of any part of the body, and how is for every day the distance from the natural state (recessus a statu naturali).¹⁵⁴

This praise should not be taken light-heartedly or as a circumstantial one: elsewhere Santorio spares no criticisms of Galen and his anatomy.¹⁵⁵ He sees his major medical achievement in bringing to completion the ancients’ project while putting it on new mathematical bases.¹⁵⁶ Both tradition and innovation are thus equally present as complementary elements in Santorio’s programme of quantification. In the light of this, attempts to present Santorio as the exponent of either the ancient physiology or modern experimentation fail, as the texts themselves stand against such simplifications. Pushed against his Galenic background—as when he addresses Obizzi’s criticism—Santorio rejects Galen and states clearly that his instruments and experiment are born out of a new methodology, unknown to the ancients.¹⁵⁷ On the other hand, however, pressed into the service of a full-scale attempt to establish a new medicine, Santorio declines the invitation and declares that his discoveries are to be applied to medicine aliquando et aliqua ex parte (‘sometime and in some respect’).¹⁵⁸ This spared him from committing himself to bombastic claims, not infrequent in his era, amongst which there are those of Descartes—who sought to replace the body with a machine, unaware as he was of the limits of quantification—and equally those of Galileo, who presented himself to Sagredo as the ‘inventor’ of the thermometer, an instrument whose applications he never really understood.

One has only to compare the use of the thermometer in the two authors, to appreciate that Galileo had no idea of how to use it. Upon realising that the instrument could allow to discriminate between real and perceived temperature, Santorio started adopting it widely, for instance to show to what extent the humidity of the air enhances the subjective appreciation of cold¹⁵⁹ or to determine the temperature of compounds, for example salt and snow, thus allowing him to show that the presence of salt doubles the effects of snow on the thermometer.¹⁶⁰ But, of course, the most important applications came as part of the everyday medical practice, for Santorio soon realised that the new instrument led to an overthrow of the Galenic rationale:

Furthermore, both Avicenna and Galen [De temperamentis Bk II] claim in this passage that our sense of touch is the judge of all <species> of heat: if the species of heat were different, the touch would not be the right judge of them. Indeed, with reference to the passage just quoted [De temperamentis Bk II] where he assigns to the touch the judgment about the equality of heat in children and young men, Galen urges us to touch many and different objects, that is to say water, at first not too hot and temperate, then the very limbs <of the body> yet according to this rule, which consists in comparing the weak to the weak, the stocky to the stocky, the fat to the fat and not the exercised people to those at rest or those fasting to those who are full. This way of measuring the degree of heat is certainly misleading. As for our part, we resort to the glass instruments […] which surely cannot mislead us. By means of these instruments we have tested whether heat is the same in children and young men. The experiment consists in placing the hand of a child and then of a young man on the glass bulb of the instrument for an equal interval of time; from this we understood that the water descent was the same in both ages which means an equality of heat.¹⁶¹

Faced with a similar problem, though eight years later (1633), Galileo finds a very different way to deal with it. The problem, proposed by Count Giovanni Bardi (1534–1612) and named after him ‘Bardi’s Problem’, proposes to explore why a person feels cold when he goes into a body of water like a river during the summer, and even colder when he comes out, but, going back into the water, finally feels comfortable.¹⁶² In his reply Galileo found no better way to investigate the temperature of air and water than ascertain it by naked hands.¹⁶³ In the light of what had already been done by Santorio, it is therefore wrong to conclude that ‘The <Bardi’s> problem, and even more so its solution, represent a paradigmatic logical model for the period before instruments had been invented to measure temperature’,¹⁶⁴ for not only did such instruments exist, but they had been put to trial on similar matters before and quite successfully. Neither it is true that no attempts had been made to set standards for the new instrument¹⁶⁵ for Santorio himself had suggested in 1630 using the fire of a candle and snow to set the maximum and minimum range of the instrument.¹⁶⁶ This suggests that Galileo played, if any, a very minor role in the process of temperature measurement.

Despite this shortcoming, in the long run Galileo’s reputation obscured Santorio’s contributions to medicine and science. As seen this was partly due to the history of science relying on the history of physics, but much responsibility also lies with the ‘unsolicited and superfluous’ apology that later Italian scholars such as Antonio Favaro and his followers reserved for Galileo, making him the benchmark and the fountainhead of every discovery made around that period.¹⁶⁷

5 Outlines for a Conclusion

Throughout this short introduction we have tried to show how Santorio’s effort to quantify metabolism by measuring the ‘insensible perspiration of the body’ (perspiratio insensibilis) turns out to be part of a wider and fully fletched programme of quantification, which grapples with the homeostatic balance of the body in its complexity: from weight change to pulse frequency, from body temperature to the humidity of the air, to the ultimate structure of matter. Out of this programme developed consequences of primary import for the history of medicine and science as a whole. Thanks to Santorio, in fact,

• Equilibrium is defined as a standard problem of ‘statics’ consisting in the capacity of the body to re-balance daily losses and gains.

• The focus of medicine is shifted from the study of multiple Galenic faculties to the evaluation of a single, fundamental and quantifiable process (metabolism).

• Instruments of precision are invented and then applied in everyday practice to correct and replace the subjective appreciation of natural phenomena.

To these merits, a fourth one can possibly be added: through the mediation of admirers and followers, Santorio’s work will open up the field to modern ‘multivariate analysis’. Indeed, while the need to provide tabulated data set according to parameters such as weight and quality of the food ingested, pulse frequency, ambient and bodily temperature, humidity of the air and barometric pressure only became explicit after James Keill (1718) and Joseph Rogers (1734) published the results of their works (Figs. 1.11 and 1.12),¹⁶⁸ the initial impetus towards this very development came directly from Santorio, who had realised the dependence of metabolism upon those very factors, pointing out the need to study them as many experimental variables. Amongst these latter—to the extent it was known and experimentally accessible to him—there was also the influence of barometric pressure on bodily processes.¹⁶⁹

Fig. 1.11

Tabulated data from James Keill’s Medicina statica Britannica (1718)

Fig. 1.12

Tabulated data from Joseph Rogers’ Medicina statica Hybernica (1734)

In the light of this, we can finally return to Daremberg’s critical remarks and contend that we fully appreciate the early modern desire of Baglivi, Lister, Boyle, Leibniz, Linnaeus, and many others ‘to erect a marble statue to Santorio’. The recognition that many of the ideas, instruments, experiments and practices that are considered central to the development of early modern science were shaped in substantial ways by Santorio and set an agenda for about two centuries, while improved versions of his instruments are still used in everyday clinics, makes us feel confident that more scholars will recognise in this figure the great experimentalist and thinker that motivated our efforts and admiration.