Culture, Medicine, and Psychiatry

, Volume 37, Issue 4, pp 601–624

Sleepwalking, Violence and Desire in the Middle Ages


    • Science and Technology StudiesUniversity College London
Original Paper

DOI: 10.1007/s11013-013-9344-9

Cite this article as:
MacLehose, W. Cult Med Psychiatry (2013) 37: 601. doi:10.1007/s11013-013-9344-9


This study discusses the phenomenon of medieval sleepwalking as a disorder of body and soul. In the thirteenth and early fourteenth centuries, medical and natural philosophical writers began to identify the category of the sleepwalker with unusual precision: the most common example of the disorder involved an aristocrat who rose, armed himself, and mounted his horse, all the while imagining that he was fighting enemies or hunting deer. Explanations for this extraordinary behaviour involved the physiology of sleep and the functioning of the brain. In particular, theorists believed that the imagination, a storehouse of images located towards the front of the brain, took control because reason and sensation had been disabled during sleep. As a consequence, daytime fears and traumas could come to the fore for some sleepers, causing them to act and react in their sleep in ways they could not, or were not willing to do, in their waking, rational state. As such, medieval medical writers viewed sleepwalking as a dangerous, disordered state which called into question the Aristotelian divide between waking and sleeping as well as the categories of reason, sensation and voluntary motion.




Questions concerning the ways in which premodern societies viewed the mind and its workings have fascinated scholars for almost a century. During that time, studies have continued to unearth the many differences between a pre-Cartesian, pre-Freudian, pre-neuroscientific understanding of the brain and our own (Bundy 1927; MacDonald 2003; Harvey 1975; Kemp 1996; Carruthers 2008). Was there a more holistic view of body and brain before Descartes? Was there a sense of an unconscious before Freud? How did theorists understand the brain’s physiology before modern neuroscience? These are, of course, massive questions that would require far more space than is allotted here. Although this essay touches on all of these topics, my primary concern is a much more modest look at several medieval understandings of the connections between psychology and physiology.

The history of medieval views on what we would call psychology remains an understudied area of research. There is, unsurprisingly, interest by scholars of religious studies, who have focussed on the rich theological materials. The Augustinian worldview, so firmly established in the medieval West, concentrated on the internal motivations for the individual’s thoughts and behaviour (Nash 1969). A new interest in intentionality appeared in the writings of twelfth-century theologians and moralists, and led to a new form of confessional culture that emphasised the interior state of the individual’s soul and mind, in particular the desires that caused sinful actions (Lottin 1954).1 Theologians explored the often morally dubious motivations behind human actions, and in the process articulated a psychology rooted in a generally negative view of postlapsarian human nature.

But by the end of the twelfth century, and particularly over the course of the following century, in the medieval West another literature explored human psychology: medicine and natural philosophy. These disciplines, recently rejuvenated by new material from the Arabic-speaking world, wrestled with some of the same problems as the theologians, but from a different perspective and for different ends (Agrimi and Crisciani 1979; Jacquart and Micheau 1990; Grudzen 2007). Medical and natural philosophical writers sought to explain the processes by which humans think and act, and as a result elaborated a complex philosophy of mind. Basing themselves largely on the writings of Aristotle, as we shall see, they explored the inner workings of the brain from a variety of viewpoints radically different from those accepted in the modern world (Pigeaud 1981).

My intention in this essay is not to provide an overview of medieval psychological theories, although it touches on a number of them. This study instead focusses on one condition identified in medieval sources as a pathology of the brain—sleepwalking—and seeks to understand it in terms of the physiological and cognitive theories of the period. I argue that this condition was uniquely positioned to allow medical and natural philosophical writers to identify connections between the mental and the somatic processes, and specifically to explore the role of the imagination in sleep.

Sleepwalking in Medieval Medicine

After having been primarily a symptom of other illnesses in earlier medical writings, sleepwalking came into its own as a category of scientific inquiry in medical sources of the twelfth century. In the decades around the year 1200, medical and natural philosophical writers began to describe a condition that seems to correspond to the modern notion of sleepwalking, but with some very particular symptoms. In these sources, the medieval sleeper performs actions associated with the waking state, just as the modern somnambulist does. But it is the type of action the sleeper performs in the medieval medical literature that distinguishes him from more recent conceptions of the sleepwalker: the medieval sleepwalker rose from his bed, armed himself, sometimes mounted his horse and lashed out with his sword at imagined enemies.

The sleepfighter, as I shall call him, appeared as the emblematic figure for this condition over the course of the thirteenth century, and then largely disappeared from the medical literature in the early fourteenth century. How and why did such a striking and specific example arise? What explanatory frameworks did medical and natural philosophical writers provide to account for this phenomenon? This study explores the different ways in which medical writers sought to make sense of sleepwalking and, in the process, elaborated upon classical views of body and mind.

Like the revenant who was thought to exist between the realms of life and death (Schmitt 1998), the sleepwalker was thought to occupy a liminal space between waking and sleeping, due to the dissonance between his actions and his sleeping state. To medieval medical writers, heavily indebted to Aristotle’s psychological writings, this combination appears contradictory and requires explanation: the sleeper by definition should not act in the ways a waking person does. In the process of analysing the phenomenon, medieval medical and natural philosophical writers were able to comment on the nature of the irrational and the imaginary, the connections between the somatic and the intellectual, and the complex roles of desire, volition and compulsion. The sleepwalker was a source not only of wonder but also of confusion and complication, as he moved both physically and conceptually between different categories: not just of waking and sleeping, but also of interiority and exteriority and of fantasy and reality.

From the late twelfth through the early fourteenth century, the figure of the sleepwalker appears in medical and natural philosophical texts as a topic of interest. The sources are associated primarily with the centres of scientific learning at Salerno, Paris and Montpellier and consist of textbooks on illnesses, medical miscellanies and theoretical discussions of physiology and mental structures. The earliest discussions come from late twelfth-century texts associated with southern Italy and the scientific learning of the area around Salerno. One writer, Urso of Salerno (or of Calabria), was a medical master connected to the school of Salerno in the years around 1200 and wrote a series of medical Aphorisms complete with their own commentaries. One of these dealt extensively with questions concerning the role of the imagination in sleep, and in the process invoked the sleepwalker (Creutz 1936).2 Closely connected to Urso’s Aphorisms are the contemporary collections of natural philosophical and medical materials now known as the Prose Salernitan Questions and easily accessible in Brian Lawn’s edition (Lawn 1979). Like Urso’s work, the various compendia of Questions incorporated the new scientific and medical knowledge coming from the Islamic world, and grappled with concerns about the natural world and how to explain it in highly materialist and often physiological terms.

Over the next 100 years, the figure of the sleepwalker appeared more frequently still, as a new wave of learning, focussed on the controversial natural philosophical writings of Aristotle, took the intellectual world of the Latin West by storm during the thirteenth century. The revival of Aristotle’s works on the natural world, which included a brief reference to sleepwalking in the treatise De somno et vigilia (On sleep and wakefulness), allowed thirteenth-century commentators such as Albert the Great and Siger de Brabant, among others, to discuss the phenomenon in detail. By the years around 1300, medical figures such as Taddeo Alderotti (1527), Bernard de Gordon (Bernard 1496; Demaitre 1980) and Peter of Abano (1482, 1483)3 were able to elaborate upon these natural philosophical ideas and incorporate them into the medical tradition.

To understand sleepwalking in this period, it is necessary to examine medieval theories of sleep, a field which has only recently been recognised to have a history of its own (Ekirch 2001, 2005; Kroker 2007).4 Yet the subject is immensely rich for those interested in many different fields, particularly because it lies at the intersection of the physical and psychological, the mentally imagined and somatically real (Hergemöller 2002).5 One can witness the act of sleeping and experience it on a daily or, perhaps more accurately, nightly basis, but its causes and internal processes remain difficult to decipher, and hence provide fruitful material for speculation. Medieval theories of the mind, for example, often included extensive theoretical discussion of the properties and purposes of sleep (Ricklin 1998, pp. 100–107; O’Neill 1968).

Sleep played many roles in medieval medicine, from the diagnostic to the curative (Palmer and Speckenbach 1990; Hoffmeister 1969; Oberhelman 1983, 1987; Pack 1966).6 I shall focus on only those aspects with a direct bearing on the issues surrounding sleepwalking, namely the physiology of sleep and its normative practice. Sleep was recognised as an intrinsic part of life necessary for the maintenance of health. In discussions of regimen, sleep was one of the so-called six non-naturals, the basic factors in retaining health or falling into illness. A Late Antique addition to Galenic medicine, the non-naturals were malleable, controllable aspects of life (we might call them the context of health or illness). Along with food, exercise, evacuations, environment and the ‘accidents of the soul’ (the emotions), sleep and wakefulness became an object to be examined and controlled in order to preserve health and avoid falling into illness (García-Ballester 2002; Gil Sotres 1998). In discussing the regimen of sleep and wakefulness, medical writers identified, often in great detail, the most healthy, ideal forms of sleep and the means of avoiding either excess or deficiency of rest; this would then maintain a proper humoral balance, and hence preserve the individual’s health (Arnau 1996).7 Alongside other necessities of life such as food, sleep was seen as an essential object of scrutiny from the late antique through the Arabic and into the western medical tradition.

Medieval medical literature considered the normative sleeper’s body to be passive, thus problematising the sleepwalker. But physiologically, the sleeping body was anything but at rest. Medical writers acknowledged the apparent quiet and coldness of the body’s exterior during sleep, but the sleeper’s external appearance belied the reality of somatic activity within. One of the main goals of the sleeping body was to digest food and, in the process, replenish the body. The sleeper’s skin appeared cold to the touch because the heat was turned inward to assist in the various stages of digestion. Nourishment was cooked or concocted by the heating process, especially as it approached the heat of the liver, and the end product of the process was the production of blood. In the pre-Harveian body, blood was consumed on a daily basis and thus had to be endlessly produced. Sleep—and the digestion that occurred during it—allowed the essential bodily liquids to be replenished and health and vigour to be restored (Bartholomaeus 1601).8 For medieval medical writers, sleep played an essential physiological role, in which movement was normally hidden from view.

Although the lower organs, such as the heart, lungs, stomach and liver, still functioned during sleep, the brain was thought to be largely at rest. This was explained by the presence of obstructive residues from the digestive process which produced fumes that moved up the body through the nerves and blocked off the brain. As a result, the senses were non-functional, and any external stimuli were ignored as the body’s attention moved inward. Most of the other parts of the brain, particularly the rational faculty and long-term memory, were equally shut off during healthy, normative sleep (Gilbertus 1510, fol. 106ra). We will soon see that one important part of the brain, the imagination or fantasy, was believed to continue functioning, allowing for dreams to occur.

The description of sleep has so far focussed on the physiological aspects and comes predominantly from the medical tradition, but there was another view of sleep, with some important differences, which derives from natural philosophy, particularly that of Aristotle. This tradition focussed on the state and geography of the mind, particularly the mental processes that could occur during sleep. In the Aristotelian natural philosophical tradition even more than in the medical literature, sleep was defined in large part by its external passivity: the body should have no sensations, and should not move, being the antithesis of wakefulness (Drossaart Lulofs 1943).9 It is this concept of the body’s external immobility that created one of the most important hurdles for medieval theorists when considering the sleepwalker.

The Sleepwalker Defined

Because the natural philosophical definition of sleep required that the exterior of the body and the senses be inactive, the sleepwalker became a seemingly inexplicable anomaly. The search for an explanation allowed medical and natural philosophical writers to articulate a variety of views on the apparent paradox. In the process, the sleepwalker began to take on a number of characteristics that may strike the modern world as unusual or unrelated to the phenomenon as we define it. The category was a large one, and included a wide variety of activities: those who debate, those who compose poetry, those children who suckle at an imagined breast, and those who wander the streets at night (the sleepwalker properly speaking, who appears very rarely in the medical literature) (Creutz 1936; Bernard 1496).10 But most often the sleepwalker was identified in the more dramatic form of the sleepfighter or even the sleephunter, who again arms himself, and then mounts his horse and goes hunting. These were no ordinary sleepwalkers.

Importantly, despite the various discussions of the ‘sleepwalker’ in the scientific literature of what I shall call the long thirteenth century, there is no precise terminology with which to identify him, nor is there a term for the condition from which he suffers. While technical terms such as lethargy, mania, insomnia (vigilia or, more rarely, insomneitas) and stupor, for example, denoted medical conditions associated with a pathology of the brain, ‘sleepwalking’ has no such straightforward nosological nomenclature, though it was also seen as a condition of the brain. The sufferer is simply dormiens, ‘the sleeper’, followed by the clear indication that the dormiens under discussion is performing actions more commonly associated with the waking state. While it might be more appropriate to use specific terms that reflect the different kinds of actions performed, for example, the ‘sleeptalker’ or the ‘sleepfighter’, it is nonetheless clear that medical writers viewed these types as different manifestations of a single phenomenon. Accordingly, I will use the more common modern term ‘sleepwalker’ for the larger category encompassing the various permutations of walking, talking, fighting, hunting and suckling that were united in the thirteenth-century sources.

The main categories of sleepwalking tended to centre around a combination of mental and physical actions. The phenomenon included many actions that have little to do with the narrow category of sleepwalking. One of the more common indications of this phenomenon was talking in one’s sleep, an act that at least should involve a correlation between the production of thought and the production of sound (although, as we shall see, one interpretation downplays the intellectual in favour of the habitual as an explanation of the phenomenon). The sleeptalker could exhibit this particular symptom in a number of ways. While some medical authors simply mentioned the process of creating speech, i.e. the movement of the lungs, vocal cords and mouth to produce recognisable sounds, others provided more precision as to what the sleeptalker was doing. So we find some who act as disputants involved in scholastic argumentation and others who cry out in fear or speak in less comprehensible ways (Creutz 1936, p. 84; Bernard 1496, fol. 68ra). Perhaps most telling is the claim that some recite or even compose verse, implying a level of memorative or creative intellectual ability unexpected in the sleeper. The movement of the lips and jaw in speech is paralleled not just by the infant as he attempts to suckle, but also by some adults who imitate the process of chewing as they imagine eating some food they desire (Creutz 1936, p. 84).11

But what dominated the thirteenth-century discussion of sleepwalking was the drama and specificity of the sleepfighter. While the sources mention talking, walking and other actions performed while asleep, medical and natural philosophical writers were fascinated by the sleepfighter’s aggressive, martial behaviour. We are told in source after source that ‘he rises and arms himself’, mounts his horse or simply brandishes his sword. Occasionally he goes off to hunt deer, but generally the emphasis is on confrontation with an enemy (Creutz 1936; Lawn 1979; Bernard 1496).12 What is perhaps most unique about the sleepfighter is the clearly drawn gender and class distinction: the sleepfighter is unmistakably male and aristocratic. The emphasis on wielding a sword, as opposed to the bow, and especially on fighting on horseback places the sleepfighter in the realm of the privileged knightly order.

The figure of the sleeper who debates, the second most commonly identified figure in the thirteenth-century literature, follows a similar pattern of historically-contingent specificity, but this time he reflects not the courtly culture of aristocratic warriors, but the new intellectual world of the period. Not only is this figure also male, but he is again part of a privileged group, in this case the scholastics trained in the art of dialectic at the incipient urban universities (Le Goff 1993; Baldwin 1970). References to men who syllogise or argue back and forth with disputants in an orderly manner remind us how historically bound these manifestations of sleepwalking were (Bernard 1496, fol. 68). At the same time, the invocation of the realms of both fighting and debating also remind us of an essential absence: medical literature seems to exclude women from the discussion of sleepwalking for reasons that are not entirely clear.

By constructing the emblematic sufferer from this condition as a warrior, medical and natural philosophical writers occasionally linked the condition with danger, specifically to those not afflicted with the condition. The association of violence and sleepfighting is taken to its logical extreme in a few cases: Albert the Great observes that sleepers ‘walk and ride horses, or sometimes they seek out and follow their enemies, and perhaps even kill them, and return to bed’ (Albertus 1890, 9.145a).13 Bernard de Gordon acknowledges the dangers associated with the sleepwalker, by suggesting with his distinctively wry humour that ‘it is a bad idea to stay in the same chamber with such friends’ (Bernard 1496, fol. 68ra).14 Such arguments introduced the issue of legal responsibility for harming others, even while asleep. There is little discussion of the topic in legal literatures, both in secular and in canon law, but it seems that the sleepwalker existed in a very unique category. In a letter to the Archbishop of Arles in 1203, Pope Innocent III had addressed the issue of responsibility for actions made by the infant, the sleepwalker (the term he uses is again dormiens, the sleeper), and the madman or demoniac, to which list we could add the drunk. His conclusion was that they were not responsible for their actions, since their rational faculty was impaired, temporarily not functioning or not yet able to function (Decretales 1881; Boureau 2006; MacLehose 2008).15 For the sleeper, the middle category applied, and the temporary lack of rational capacity, as we shall see, helped to explain much of the sleepwalker’s behaviour.

The sleepwalker was generally an abstracted, hypothetical case (or series of cases), as was common in medieval discussions of diseases and their sufferers. The descriptions were copied from text to text and we have no way of judging the reality or frequency of sleepwalking, let alone the specificity of sleepfighting. But we do have some evidence of people who actually suffered from sleepwalking, although revealingly none of them were sleepfighters. In a passage from the second half of the thirteenth century, the physician and Bolognese professor of medicine, Taddeo Alderotti, discussed the category of the sleepwalker in his commentary on the Isagoge of Johannitius, the basic text of medieval medicine which laid out the fundamentals of Galenic theory. In the passage, Taddeo admitted that he himself suffered from this condition: surgentibus de nocte quorum ego fui unus, ‘those who rise at night, of whom I am one’. He does not specify what he actually did while asleep, except to note that, while sleepwalking, he fell from the height of four feet without waking (Taddeo 1527; Siraisi 1981). We will return to Taddeo when discussing the various interpretations of the causes of sleepwalking.

Albert the Great also mentions a sleepwalker he had met, and adds some important considerations to the discussion. Like Taddeo’s self-admission, Albert’s incident is not a case of sleepfighting but of the far less dramatic act of sleeptalking. In his commentaries on Aristotle’s De somno et vigilia, written probably between 1254 and 1260, Albert discusses the Aristotelian problem of ‘those who in sleep perform the actions of those who are awake’. He tells us that he has ‘seen and heard a certain man do this, who when asked a question raised himself in his bed, responded, and lay back down, having dismissed the questioners; he was asleep the entire time he did these things’ (Albertus 1890, 9.145a).16 Here the focus is primarily on the ability of the sleeper to interact verbally with those around him, but Albert makes it clear that the physical movements matter as well: the sleeper’s ability to prop himself up and return to a prone position are part of the performance. We do not know enough about this incident, if indeed it actually happened, but the scenario inspires some intriguing suggestions: did Albert and the others who had gathered around the sleeper know the man had such a habit (why else ask questions of a sleeper)? If so, was this some sort of experiment or desire to witness such an event, even if it were manipulated externally, by the questions asked of the sleeper? How much was Albert aware that this could contradict the views of Aristotle, that it implied that the sense of hearing—and the intellectual capacity to comprehend and respond—was not entirely removed, and that the incident involved external reality as much as the internal workings of the imagination? For Albert, the actions involve either the fantasy or the intellect in a very novel argument, since the intellect was generally associated with the rational faculty, which was not functioning during sleep. Albert interprets the Aristotelian view by noting that the sleeper acts by means of the fantasy or imagination, a term of central importance to this subject, as we shall see. Whatever may have triggered the actions, Albert argues that this sleeper is ultimately responding not to the actual individuals in front of him but to images he sees in his sleep, aided by his sense of hearing (Albertus 1890, 9.145b).

It is not at all clear why the figure of the sleepfighter should become so prominent in the later twelfth century. The revival of Greco-Arabic learning, and particularly of Aristotle’s interest in the phenomena of sleeping and waking, may explain the appearance of questions that considered an intermediary space between the two states. But there is no obvious source for the specificity of the sleepfighter. We find some connections to—and perhaps a partial source for—this figure in the dream theories available to the Latin west. The fifth-century theorist of dreams, Macrobius, whose influential Commentary on the Dream of Scipio circulated often in Europe during the twelfth century, discussed the different types of dreams and identified some as essentially anxiety dreams. He even used as an example the idea of a man who ‘fears the plots or might of an enemy and is confronted with him in his dream or seems to be fleeing him’ (Stahl 1952, p. 88; Macrobius 1963, p. 102) It is possible that the medical and natural philosophical writers of the twelfth and thirteenth centuries elaborated on the (dreamed) physical reaction described in Macrobius’ text. But whether or not this is so, the medical sources pushed the discussion in a very different direction.

Medieval dream theorists did not generally discuss the possibility of sleepwalking, despite the various connections between the phenomena. The history of dreams has been well studied, far more so than the history of sleep, and certainly provides some parallels with the sleepwalker’s predicament (Kruger 1992; Gregory 1985; Le Goff 1980; Dulaey 1973; Miller 1994; Paravicino Bagliani and Stabile 1989). Generally, however, theoretical discussions of dreams and the more practical manuals for interpreting them were focussed on ‘meaningful’ (prophetic) or allegorical visions. Saint Augustine acknowledged that dreams often derived, at least in part, from bodily or mental stimuli, but downplayed the relevance of the purely corporeal dream visions (Kruger 1992, pp. 39–41). The twelfth-century natural philosopher William of Conches also acknowledged the importance of dreams that were not entirely prophetic or divinely-inspired. William further divided non-divine dreams into those that arose from the soul (meaning from emotional or internal spiritual concerns) and those that arose purely from somatic processes, but equally relegated these two categories to the bottom of his dream hierarchy (William of Conches 1965, p. 242; Kruger 1992, p. 78).

Macrobius’ division between various types of significant dreams and the more simple and unimportant category of anxiety dreams served as an excuse for medieval dream theorists to disregard the latter category as unworthy of much discussion (Ricklin 1998). Their causes and meanings were considered to be straightforwardly obvious and individualised, and did not reveal greater truths or have future significances. Indeed, the anxiety dream seemed to look only to the (recent) past of a single individual, rather than point to a future event. The strict dichotomy between celestial influences and prophetic dreams on the one hand and material, somatic influences and mundane dreams on the other was generally maintained throughout the central middle ages and beyond. According to such an oneiric taxonomy, the types of dreams with which we are concerned were relegated almost exclusively to the mundane world of medical pathology. Empty of larger significance as they may have been to the interpreters of dreams, the images that inspired sleepwalkers to act while asleep also inspired medical writers to analyse them and discuss their implications in terms of cognitive functioning. It is to these images that we now turn.

Searching for Explanations: The Imagination and the Brain

Having identified the characteristics of the medieval sleepwalker, we can now consider the medical and natural philosophical attempts to explain the condition. In what theoretical framework did the unique and potentially dangerous behaviour of the sleepfighter make sense? How could he move when he should be immobile and unresponsive in slumber? Or conversely, how was he asleep if he was performing actions normally associated with the waking state? Medieval writers frequently posed these questions and, as we shall see, the medical and natural philosophical traditions provided a number of possibilities for answering them.

To understand the medieval sleepwalker, we must recognise the differences between the medieval brain and its modern counterpart. From the middle of the eleventh century onwards, western understandings of the topography of the brain followed a tripartite structure, with three compartments or cells, each of which served important and differentiated functions. In the first or anterior part of the brain was the common sense, which pulled together sensations from all five senses and attempted an initial interpretation of their meaning. Still within the anterior cell of the brain but behind the common sense, lay the imagination (imaginatio) or fantasy (phantasia), which retained these sensations for later use, becoming a kind of temporary storehouse (thesaurus) of images. The second or middle compartment contained the cogitative and estimative powers which included the ability to reason and to distinguish right from wrong (Avicenna 1963; Kemp and Fletcher 1993; Harvey 1975; Kemp 1996). The third, posterior cell of the brain was associated with memory—more permanent than the fleeting nature of the imagination—which connected a sensation with a host of other individual memories and with a generalised knowledge thought to be common to all sentient humans. This theory of the mind and topography of the brain arose from classical, Islamic and early medieval traditions, although there were many variations on it. Aristotle, for example, had advocated the existence of the common sense and the imagination, but had not specified where these mental processes took place (Wijsenbeek-Wijler 1978; Bundy 1927; Wedin 1988; Gregoric 2005). It was only later Greek and Arabic writers who articulated a more precise geography of the brain and its functions (MacDonald 2003).

The brain’s role in sleepwalking was emphasised throughout the literature, an emphasis that is perhaps unsurprising given the classification of this condition as a disease of the brain. One physiological explanation of sleepwalking returns us to the digestive process, but this time identifies an occasional abnormality which could affect the functioning of the brain. As with the normative model, a fume or smokiness arose from the stomach’s concoction or purification of the food, and moved upwards and tried to render the brain inoperative, but sometimes the passageways of the nerves were too wide or the smoke too thin to block them. As a result, since the passages of the nerves were not completely obstructed, some sensation or ability to move remained, especially in those of a melancholic or choleric temperament (Lawn 1979, B37, K8 and V8). An anatomical anomaly and a humoral predisposition thus accounted for at least the possibility of movement. Such largely physiological explanations of sleepwalking were in fact often connected to an individual’s predominant humour or quality, as in the analysis by Peter of Abano in his Conciliator. Peter argued that those with hot and dry brains were more prone to sleepwalking, focussing on the individual’s general constitution rather than a specific physiological incapacity (Peter of Abano 1483).17

But it was the brain’s intellectual functioning that was paramount in the thirteenth-century discussions of the sleepwalker. Although the brain—and especially the senses, reason and memory—was largely inactive in sleep, nonetheless the imagination was considered the one part of the brain which continued to function and in fact was thought to remain active at all times. It was in the front cell of the brain that fragments of sensations were collected during waking hours. The two terms used to describe these remaining fragments, imago and phantasma, refer to visual sensations, and the imagination or fantasy was indeed most often seen as an initial repository of fleeting images taken from the common sense. Nevertheless, the imagination could include non-visual stimuli, including those derived from the senses of hearing and taste (Kemp 1996, pp. 561–564; Kenny 1993). These stimuli or fragmentary relics of recent experiences were recalled and reactivated by the imagination during sleep. Such recall could lead to dreams or nightmares, and could cause the responses seen in the various manifestations of medieval sleepwalking.

Three Explanatory Models

In discussing the phenomenon of sleepwalking, medical writers clarified the role of the imagination by identifying three ways in which the sleeper’s thoughts and actions were influenced by the imagination. It is these three models, of habit, desire and fear, that allowed thirteenth-century writers to explore the role of the brain in the physical activity of the sleepwalker. As a consequence, they applied to the topic of the sleepwalker the concepts they had inherited from the ancient world, and attempted to push them in new psychological directions.

For Urso of Salerno around 1200 and Albert the Great a half-century later, the sleeper’s imagination is heavily influenced by the habits, desires and fears of the waking state. After discussing the different types of movements which sleepers exhibit, Urso notes that they occur due to the fantastic virtue (virtus fantastica), that is, the active power of the imagination, which works through the soul to create the images that will appear in the internal vision of the sleeper. Once the fantastic virtue is incited by the physiological processes of digestion, Urso tells us, ‘the sleeping animal is more inclined to imagine those things, at which it is accustomed to toil with the full attention of the mind [while awake]’ (Creutz 1936, p. 83).18 The use of the term ‘animal’ is difficult to decipher but there is some logic in the apparent connection between the human sleepwalker and the animal world. What distinguished humans from animals is our ability to reason, according to the common Platonic–Galenic theory which distinguished three types of living things: the vegetative, the animal and the rational. Because the rational faculty was inoperative during sleep, humans while resting could be comparable, at least in terms of mental processes, to animals (Albertus 1890, 35.399a).

The Model of Habit

This explanatory model for the sleepwalker is based on what we can call the motif of habit or customary behaviour. That is, it is founded on the idea that the brain recreates in sleep images taken from the common, repeated events and thoughts of the day. That the individual would focus his waking attention on his duties or occupation (preparing for battle or for a public debate, for example) is here assumed to be normal and appropriate. However, this close concentration on one’s daily tasks imprints itself upon the imagination, which will retain the memory and may return to it in a vivid form while asleep. Hence, with the right combination of physiological factors, for example, when the nerves were only partially obstructed or when the brain was too hot and dry, the sleeper could perform a sort of pantomime, mimicking his daytime habits and responsibilities. Alain Boureau has argued that the sleepwalker in the Prose Salernitan Questions is essentially of this type, an automaton, performing during sleep the activities he would customarily engage in while awake (Boureau 2006, pp. 152–154). This argument is in part correct, but presents only one aspect of the larger and more subtle picture painted in the sources. In fact, medical and natural philosophical writers provided multiple explanations and focussed on the interplay of physiological and what we may call psychological components in the explanations of the condition.

The thirteenth-century scholastic penchant for multicausal explanations is clear in a number of sources. Albert the Great argues that sleepwalking is caused by two things: either a strong impression of something to be done in the future or an impression of some things that are done by habit. As a consequence, because some of the senses are weakened during sleep while others are not, some movement can occur, as when a person talks—or moves his tongue as if to talk—or a child licks his lips while imagining the mother’s breast. Unfortunately Albert doesn’t expand on the idea that sleepwalking is caused by such images or thoughts of future duties (Albertus 1890, 35.399a). Nevertheless Albert’s works were immensely influential, and these passages were repeated in the famous encyclopaedia of Vincent of Beauvais (1624), a massive compendium of scholarly knowledge compiled in the middle of the thirteenth century, shortly after Albert wrote his text.19

Several decades later, in the 1270s or 1280s, Taddeo Alderotti, whom we have already encountered as a self-confessed sleepwalker, argued that such patients only act out of spatial familiarity and customary behaviour. He begins with a negative arguments: those who ride horses while asleep, he tells us, do not go to the stables if they are in a house with which they are not familiar (Taddeo 1527, fol. 362ra). Taddeo implies that the sleepwalker has some awareness of where he is, and that his movements are contingent upon that prior knowledge and habit. Taddeo later draws a revealing analogy: the sleepwalker is like one of Taddeo’s colleagues, a blind university master who wanders the streets of Bologna alone (Taddeo 1527, fol. 262rb).20 The blind man is able to cross the city streets without assistance because he acts out of custom and intimate knowledge of his surroundings, and the sleepwalker is led by his imagination in a similar way. This unlikely comparison of a physical disability and a disorder of sleep is used as evidence that the sleepwalker does not need the senses (in this case, sight) in order to move in recognisable ways.

The Model of Desire

The imagination was thought to be excited or inspired not just by ingrained, daily habits but by the more fleeting wishes and desires experienced by the individual during the waking state. When addressing this second type of influence on the imagination, an influence we will call the model of desire, Urso of Salerno comments as follows: ‘when one notices something he desires to have, knowing that he cannot have it, he is moved toward his desire by an anxious intention, and thus the soul in sleep excites the imaginative virtue to show to the animal the form of the desired thing’ (Creutz 1936, p. 84)21 While once again Urso’s use of the term ‘animal’ here is obscure, the meaning is clear, with its emphasis on the impact of waking desires on the sleeping state. The human’s rational faculty is not operating, and thus cannot restrain these desires. As a consequence, the human while asleep and the animal while awake share the same unbridled power of the imagination.

A good illustration of the implications of these first two models can be found in Albert the Great’s discussion of the child who moves his lips while sleeping and imagines himself nursing at the breast. The example is explained in two very distinct ways, one based on the habit-model and the other coming out of the desire-model. In the first explanation, the child may move his lips in a way suggesting he is suckling because he is simply repeating a frequent waking activity and so he is simply acting out of habit. In this case, the child would be acting reflexively as an automaton, in Boureau’s sense of the term. Or conversely the child may act out of desire: he imagines himself at the breast because he desires the sustenance that would result from his actions (Albertus 1890, 35.399a; Creutz 1936, p. 84).22 Sleepsuckling and other examples of the phenomenon could be interpreted in different ways, depending upon which model was invoked. This second of Albert the Great’s interpretations moves us into a realm very different from that of habit, into one of desire and imagined fulfilment.

The Model of Fear

But there is a third category of influence on the imagination, alongside repetitive daily actions and desires, and that is the model of fear and anxiety. This category in one sense connects the other two, but is demonstrably different enough from them to warrant separate discussion. It also provides some further parallels—though nothing more than that—to much more recent concepts such as dreams as wish fulfilment. In Urso of Salerno’s Aphorisms and in several manuscripts of the Prose Salernitan Questions, we encounter a sleepfighter who is able to overcome his fears and face the enemy he had been unable to meet in combat during the day (Creutz 1936; Lawn 1979, B207 and V8). The writers invoke the idea of audacity as something that these warriors can attain in sleep when they could not do so while awake.

In a similar vein, Bernard de Gordon transforms the sleeper’s walk (one of the few examples of a somnambulist properly speaking!) into a journey associated with daytime fears and prohibitions: ‘sometimes they go through inaccessible places, which in wakefulness they would in no way have dared or been able to pass through’ (Bernard 1496, fol. 68ra).23 He does not clarify what makes these places so impassable or inaccessible (invia) but the implication is that these actions are distinctly not a rehearsal of the individual’s habitual actions while awake. This sleepwalker directly contradicts Taddeo’s argument that people did not sleepwalk in unfamiliar places. Instead, these actions push the sleeper into new areas and past impediments that he would encounter during the waking state.

It is very clear that the state of the sleeper’s mind was thought to play a major role in the types of images and their influence on the brain. Urso of Salerno emphasises that the emotion of fear and a state of anxiety are associated with the waker’s soul, which brings the images to the brain (Creutz 1936, pp. 83–84). In his commentary on the pseudo-Aristotelian Problemata, Peter of Abano discusses the disturbances of the mind that could cause sleepwalking (Peter of Abano 1482; Siraisi 1970).24 A movement of the mind, by which the writers mean a mental disturbance, produces these images in the sleeper’s brain. In the Prose Salernitan Questions, we find a reference to the sleeptalker, who speaks because his soul was anxious (anima sollicita) during the day about some secret thing, which he then unintentionally reveals in his mutterings while asleep (Lawn 1979, V8). The sources associate the soul with the mind here, or at least with emotional disturbance, sometimes identified with the idea of movement (motus mentis). Does the motion or commotion of the soul lead directly to the motion of the sleeper’s body?

How to explain the imagination’s ability to manipulate the supposedly unmoving sleeping body in a way that acts out the images in the mind? The solution to this dilemma brings us back to the physiological state of the body during sleep. While the ability to feel external sensations (made possible by the virtus sensitiva, the sensitive power) has been incapacitated, the same cannot be said for the ability to move (virtus motiva, the motive power), which remains at least potentially active (Lawn 1979, V8; Albertus 1890, 9.145b and 35.399a). This motive power allows the sleeper to move from side to side, and is usually separated from the brain’s control in sleep. However, when the nervous passages are not fully obstructed and the imagination brings the sleeper’s daily activities, desires or fears to the foreground, then this imagery in the brain can induce the motive power to act (Albertus 1890, 9.145b). The separation of sensation from movement is essential to the distinction between the actions of the sleeping and waking states. It is also that which connects all of the categories of sleepwalking: to move one’s lips and to mount a horse for a midnight hunt, all while asleep, might seem to be utterly different phenomena, but they are united by the notion that the imagination has influenced the motor faculty. Even in sleep, the mind—or a portion thereof—was thought to control or at least influence the body.

The power of the imagination in sleep can be seen most forcefully in an exceptional case, that of King Henry I of England, the only example I have found that provides any kind of parallel to the sleepfighter in a non-scientific medieval source. The story of Henry I’s dream, relatively well known for its social and art historical significances, appears in John of Worcester’s Chronicle under the year 1131. We learn that, while staying in Normandy, Henry received three disturbing dreams in which he was first confronted by angry peasants, then by aggressive knights and finally by clerics, all three groups protesting unjust royal behaviour. The dreams and the accompanying illustrations depicting a sleeping Henry visited by each group who together represented the tripartite structure of society, has received considerable attention, but Henry’s responses to the visions have often been overlooked (John of Worcester 1998, pp. 200–203; Collard 2010; Duby 1980; Carozzi 1989; Kealy 1981). After the first two dreams, we are told, Henry rose quickly from his bed and, grabbing his sword, defended himself vigorously against the imagined assailants. The chronicler tells us that the royal guards had fled the royal bedchamber, terrified by his violent outburst, before Henry realised that the images were false. John of Worcester notes that these dreams arose because the monarch had treated these three groups unjustly, with the implication that this was a monitory or possibly an anxiety dream. Henry’s act of self-defence as he awakes and brandishes his sword places him momentarily between states; the images or phantasms from his sleep creep into his waking state, or perhaps more accurately his wakefulness has intruded on his dreams. Henry’s response is not an example of sleepfighting in the sense used by the (later) medical sources, but alludes to an intermediary state between waking and sleeping. What is most important here is the vivid nature of the visions produced by the king’s imagination and the emotional and physical responses they provoke.

The power of the imagination can perhaps provide a solution to a question left unanswered earlier: Why were the examples of sleepwalking gendered as male? It could be simply that the medical model was almost always implicitly or explicitly male. But imagination itself was a gendered concept: medical authors viewed women’s imaginations with considerable apprehension (Lemay 1992).25 It is well known that medieval theorists considered women in general to be more susceptible to their desires and imaginations. This is most clearly seen in medical views of pregnant women, especially the idea of the maternal imagination, which was considered so powerful that a woman’s excess desire for something could affect the shape and health of the foetus (Huet 1993). If women were viewed as more prone to desire and less rational, then perhaps these moments of male non-rational behaviour were more exceptional, surprising and worthy of comment? Perhaps it is that, precisely because men were thought to be more able to act rationally and control their imaginations, the very idea of male sleepwalking required greater explanation and became a medical phenomenon?

Perhaps the most (literally) striking reminder of the strength of the imagination during sleep appears among Bernard de Gordon’s cures for sleepwalking. Alongside the more typically medical advice of bloodletting and pharmacology, Bernard includes an exceptional suggestion: ‘and also as they are beginning to rise [from their beds], whips are very useful, to distract them from such imagination’ (Bernard 1496, fol. 68ra-rb). The use of whips may surprise us, although it is not the only place where the Montpellier medical master advocates their use,26 but the explanation helps to rationalise the treatment. The sufferer is overwhelmed by the images he sees through the power of his imagination, and so he must be diverted from them by all means available. Bernard does not mention if this is an attempt to awaken the sleeper or simply to shift the focus of the sleeper’s thoughts, but either way he suggests the tenacity by which the imagination holds the sleeper in its thrall. Imagination, it seems, can—and sometimes should—be tamed or at least restrained.

This awareness of the extent of the imagination’s hold over the sleeper can be found in Albert the Great’s work as well. Albert indicates that the sleepwalker, whether talking, fighting or acting in any capacity, is so engrossed in his tasks that it is very difficult to interrupt him or bring him back to the waking state (Albertus 1890, 9.146a). The internal vision which guides the sleepwalker is so all-consuming that it almost entirely excludes external stimuli from his awareness, as also seen in Taddeo’s comment about falling without waking. But the single-mindedness of the sleepwalker is entirely understandable within the logic of medieval physiological theory, since the primary negative definition of sleep—as that period during which the external senses and the rational faculty are not in operation—serves to explain the almost complete hold that the imagination has over the sleeper. With sleepwalking, the imagination can, almost literally, run wild.

The imagination, reviving and reassembling images and experiences from the waking state, plays an important role in many medieval medical conditions of the brain. But sleepwalking stands in a strange relation to other disorders of the brain and of sleep. The closest pathology is nocturnal pollution, which was thought to share an inability to prevent the desires of the waking state from affecting the body. Both sleepwalking and nocturnal pollution emphasise the power of the imagination and particularly the impact of unrestrained desire (Elliott 1999).27 On a different level, the medical condition known as the incubus, something akin to modern ideas of sleep paralysis, was thought to arise from a similar combination of physiological and mental causes. Medical theorists noted that the incubus patient became temporarily paralysed due to internal somatic causes (most often indigestion), and this inability to move produced fear in the sleeper’s imagination, which then interpreted the phenomenon as an external, demonic attack (Van der Lugt 2001; MacLehose 2013). Similar issues of the irrationality of the sleeper and the influence of the imagination arise in various medieval medical categories related to sleep.

Beyond Aristotle’s Strict Divide

The debates over the sleepwalker took on renewed resonance over the course of the thirteenth century with the introduction of newly available Aristotelian material, particularly the treatises De anima and De somno et vigilia. In the latter text, Aristotle makes an absolute distinction between the two states of being: sleeping is the negation of waking (Drossaart Lulofs 1943; Aristotle 1984 pp. 721–728). But at the same time, there is a tantalisingly short passage in the text, in which Aristotle argues that there are ‘sleepers who do the work of waking people’. Other pathological conditions associated with waking and sleeping, such as profound sleep, an almost coma-like state, or insomnia, a state of excessive wakefulness, follow the binary opposition of the states. But here we find a pathological state which does not follow the definitions and divisions of sleeping and wakefulness (Holowchak 1996). Aristotle simply tells us that this phenomenon can happen because of phantasmata (images in the brain) and some sensation. He says nothing more about the causes of the phenomenon, nor does he define what the actions are or what the link is between the actions and the images. It was left to his followers to explain the seeming contradiction in this passage.

To remove the apparent contradiction, natural philosophers turned to medical materials and incorporated them increasingly during the thirteenth century in their discussions of the Philosopher’s thoughts. In his immensely influential commentaries on the Parva naturalia, including De somno et vigilia, the twelfth-century natural philosopher from Muslim Spain, Averroes (Ibn Rushd, died 1198) emphasised the power of the imagination and the divide between waking and sleeping (Averroes 1949, pp. 96–97, 117, 124). Albert the Great’s works also continued to accept the Aristotelian dichotomy between the two states (Mahoney 1982). Following Aristotle’s brief reference, Albert had argued that there must be some sensation in the sleeper, although it is diminished. But Siger of Brabant admitted the difficulty of the question, arguing that a vivid impression on the imagination must have excited the internal, rather than the external, senses; and thus, set in motion the organs associated with motion (bear in mind the distinction made earlier between sensation and movement). For Siger, the impression is not necessarily a visual one; instead he identifies the passions of the soul, the emotions, as a source of impressions: extreme joy or sadness—like the sleepfighter’s fear—may excite the body to act (Van Steenberghen 1931, pp. 226–227).

Yet there were alternate understandings of the sleepwalker’s relation to the outside world. The unusual status of the sleepwalker receives extensive discussion in Bernard de Gordon’s Lilium medicine, dated to 1304, where the condition is discussed under the disease category vigilia, wakefulness or, in its pathological state, insomnia. Bernard makes it clear that the sleepwalker is indeed asleep, but because of its anomalous nature he associates sleepwalking not with other pathologies of sleep but with a medical pathology of the waking state (Bernard 1496, fol. 68ra). In the course of his discussion, Bernard emphasises the power of imagination and its often negative impact: while sleeping, the mind could turn upward to higher things and could argue logically (syllogizare) or compose verses. But Bernard wryly notes that ‘it is easier to descend than to rise’, and consequently when we sleep ‘we are in constant torment’ by fantasies and dreams (Bernard 1496, fol. 68ra; Avicenna 1968, pp. 20–22).28 Citing Avicenna’s De anima, Bernard argues that the images that appear to the sleeper through the imagination depend heavily on the state of the individual’s soul, in particular its level of peacefulness or anxiety.

More importantly Bernard de Gordon breaks down the strict Aristotelian duality of sleep and wakefulness. After describing the audacity of the sleeper in facing previously-feared enemies or entering places he had not dared to go before, Bernard makes an important, if tantalisingly underdeveloped, observation: these examples of sleepwalkers reveal an important and novel truth, ‘sleepers are therefore awake [dormientes igitur sunt vigilantes; literally, those who are sleeping are therefore those who are awake]’ in that ‘they see the lights of lanterns, but dully and hear the cock crow, but faintly’ (Drossaart Lulofs 1947).29 He explains this by repeating the statement about sleepers as wakers and returns to the Salernitan notion of the obstructed openings, with some additions: such patients have a hot and humid complexion of the brain and therefore the humidity obstructs the external senses and the heat increases the imagination. The sleeper may be able to feel some sensations—sight and hearing are identified here—but he does so in a diminished capacity. Instead of Albert’s sleepwalker who is seemingly oblivious to the world around him, the sleepwalker in Bernard de Gordon’s formulation is a figure who stands at a crucial position between two worlds. Yes, the imagination (virtus imaginativa) has largely taken charge and leads the sleepwalker to act and respond to the images he sees, but Bernard notes that even here there is room for the external senses. By taking the Aristotelian definition at face value, Bernard notes the seemingly insurmountable contradiction between the sleepwalker’s actions and his state of being, and takes it to its logical conclusion: the sleepwalker seems in part to demolish the basic division between waking and sleeping.

Many things remain unexplained in Bernard’s passage on sleepwalking in the Lilium medicine as in the other sources. The interplay between physiology and the passions is not resolved; it is not clear how the mental faculty is active but only partially so; nor is it clear what else might occur when the irrational and the arbitrary have control. Sleep and sleepwalking become problematic because of the lack of control by the rational part of the brain or by the estimative faculty, which ought to interpret such images in a proper and rational way. The sleeper’s imagination can control not just the sensations in the brain but also, as a consequence, the actions of the body, leading to acts of unknowing bravery or even of criminal behaviour. It is the possibility of both movement and sensation that causes Bernard de Gordon to reconsider Aristotle’s divide between waking and sleeping states and thus to explore the darker side of the human psyche, where, as Bernard tells us, headless creatures and other monstrous images abound (Bernard 1496, fol. 68ra).30


To medical and natural philosophical writers of the thirteenth century, the sleepwalker posed an intriguing problem, particularly concerning the relation between bodily and mental processes. Those who sought the causes of the condition articulated a variety of explanations, from the purely somatic to a mixture of bodily and brain activity. In the thirteenth-century sources, various attempts to understand the sleepwalker led to new observations on the role of the brain and the imagination. The sleepwalker was not simply somatically enacting the images that appeared in his head, but also enacting the desires and fears that had produced those images. One physician, Bernard de Gordon, used the sleepwalker as the basis for a lengthy discussion of the heights and depths, the hopes and fears, of the human mind: even while sleeping, he noted, we are capable of producing thoughts that are sublime and rational on the one hand or lowly and nightmarish on the other. Bernard complicated the basic Aristotelian divide between wakefulness and sleep when he argued that the sleeper could potentially think rationally or experience, even faintly, the senses of sight or hearing.

As we have seen, the sleepwalker was only one of several exceptional states of being whose larger significances physicians and natural philosophers sought to identify. The sleepwalker’s lack of rational and voluntary control over his own body and actions found connections to the demonically possessed or mad (Caciola 2003). The ghost or revenant existed between states and generally did not respond to external stimuli, like the sleepwalker (Schmitt 1998). Those who experienced nocturnal emissions also exemplified the blurring of dream vision and somatic response, with occasional moral implications. The medical sources do not address the moral responsibility of the sleepwalker but they do express considerable interest in the connections between upper and lower parts of the body, images and action, sensations and involuntary motion, the relation of soul to brain, and some interest in the state of the soul in sleep.

To study the sleepwalker was, for medieval natural philosophers and doctors, a means of exploring the liminal state between waking and sleeping. They recognised that the sleeper could act on desires derived from the waking state, desires otherwise restrained by the rational faculty while awake. The sleeper interacts with the outside world yet does not seem to recognise that world as a waking person would. That is, the external world with which he interacts is based on the internally produced visions stored in his imagination. The world that the sleeper ‘sees’ has little to do with the actual world around him. Instead, the world experienced by the sleeper derives for the most part from the storehouse of images taken from daily life or from thoughts and desires experienced by the sleeper during the day. The sleepwalker was thought to overcome the constraints and fears he felt during the day, in order to satisfy his wants and/or act with bravery and comparative fearlessness.

Sleepwalking provided medical writers with a case study of the workings of the imagination or fantasy. The imagination did not cause desire but retained a memory of desires and aspirations from the waking state and allowed that memory to come to the fore during sleep. Sometimes these images or memories led to simple repetition of daily activities, and other times they allowed the sleeper to overcome fears and act on desires. The specificity of the actions often corresponded to the sufferer’s social status: noblemen fought or hunted, and university men lectured or debated. The turmoil and tedium of the waking state became the basis for the sometimes elaborate scenarios described in the medical texts. Sleepwalking allowed medieval medical authors to study the connections between thoughts or images and actions, between mental processes and somatic responses. In the thirteenth-century medical literature, the medieval sleepwalker became a participant in an internal drama of the imagination, played out not simply in the mind but also in the world of flesh and blood.


The formative text on the subject remains Lottin (1954), p. 6 volumes. For Augustine’s philosophy of mind and psychological framework, see Nash (1969).


See Creutz (1936), aphorism 41, Vi animae vel consuetudine seu compassione in sompnis, fantasiae diversificantur, pp. 74–84.


Discussed in both his Conciliator and his commentary on the pseudo-Aristotelian Problemata. See Peter of Abano (1482, 1483).


Research on sleep is still in its infancy, and received its first inspiration from Ekirch (2001, 2005). See also Kroker (2007).


There is next to nothing on medieval sleep, despite a large literature on dreams, mostly written by literary scholars, with the exception of Hergemöller (2002).


I am working on a full-length study of the medical meanings of sleep in the middle ages. On sleep and diagnostics, see Palmer and Speckenbach (1990) and Hoffmeister (1969). For the classical origins of the medical dream diagnosis, see Oberhelman (1983, 1987), as well as Pack et al. (1966).


For an overview of sleep in regimen literature, see Arnau (1996), ch. 4, La higiene del sueño.


The thirteenth-century encyclopedist Bartholomaeus Anglicus provides a summary of the scholastic viewpoint circa 1230, including references to Aristotle, Augustine, Avicenna and Constantinus Africanus (the Pantegni). See Bartholomaeus (1601), 6.24, De somno, pp. 266–269.


Drossaart Lulofs (1943) includes the two main medieval translations of De somno. Most commentaries on De somno remain unpublished; see the discussion below for Albert the Great, Averroes and Siger de Brabant’s commentaries.


The more extensive sources list many of these types of ‘sleepwalking’; see Creutz (1936), pp. 47–48; Albertus (1890), 9.145a; Bernard (1496), fol. 68ra.


Creutz (1936), p. 84 on ‘comissationi et ebrietati intendentes… cibis ymaginatione praesentatis dormiendo malam et os movet in tantum, ut modus commasticationis stridore dentium cognascatur’.


Urso and the Prose Salernitan Questions mention rising, arming and occasionally mounting a horse; Bernard de Gordon mentions the desire to hunt deer. In my favourite example illustraing the danger of homonyms, the 1496 edition mistakenly replaces the word cervum [deer] with the word servum [a servant or serf]! The two words would not have been homonyms in Italian or German, but the edition was published in Lyons, where it was possible to conflate the two words.


Albertus (1890), 9.145a, De somno et vigilia 1.2.5: Tamen in somno quidam moventur et faciunt multa opera quae sunt vigilantium, sicut est ambulare et equitare, et aliquando quaerere et insequi inimicos, et forte occidere eosdem, et redire ad lectum dormientes.


Bernard (1496), fol. 68ra: et ideo malum est in vna aula cum talibus socijs habitare.


Innocent III, Epistola Arletanensi Archiepiscopo, in Decretales (1881), lib. 3, tit. xliii, cap. 3; see also Boureau (2006), pp. 156–159. On the context of this letter, dealing with southern French heretics’ rejection of infant baptism, see MacLehose (2008), ch. 2 and appendix.


Albertus (1890), 9.145a: De somno et vigilia, 1.2.5: Et vidi ego et audivi quemdam hoc facientem, qui interrogatus elevavit se in lecto, et respondit ad interrogata quaerentibus et reposuit se, illis dimissis, et continue dormivit, dum hoc faceret.


Peter of Abano (1483), differentia 157 [unpaginated, final page of differentia]: cum videamus aliquos de lectibus surgere seque armantes quandoque procedere aut huiusmodi peragere et maxime quorum cerebrum est calidum et siccum.


Creutz (1936), p. 41, p. 83: Ad ea ymaginanda dormiens animal magis inclinatur, in quibus tota mentis intentione insudare consuevit.


Vincent of Beauvais (1624), Speculum naturale, book 26, quotes from Albert’s Summa de creaturis, stripped of its scholastic format by reducing the quotations to only the solutiones.


Taddeo (1527), fol. 262rb: sed vadunt propter consuetudinem sicut magister compagus cecus qui vadit propter consuetudinem per bononiam transeundo vias sine aliquo socio.


Creutz (1936), p. 84: Inde est quod aliquis quandoque aliquid conspicit, quod ipse habere desiderat, quod sciendo dum habere non potest, ad eius desiderium sollicitiori intentione movetur. Unde anima in somnis virtutem ymaginariam excitat ad appetitae rei formam animali monstrandam.’.


Albertus (1890), 35.399a, Summa de creaturis, 43.5.3: quibusdam pueris qui videntur mammas sugere in somnis. Urso of Salerno includes a considerable discussion of the model of desire as well: Creutz (1936), aphorism 41, p. 84.


Bernard (1496), fol. 68ra: Aliquando vadunt per loca inuia, ita quod in tempore vigiliarum nullomodo auderent vel possent transire.


Peter of Abano (1482), part. 8, prob. 8.


See especially the introduction to Lemay (1992).


The use of whips appears again in Bernard’s discussion of nocturnal emissions, in this instance to restrain or distract the mind from sexual thoughts during sleep. See Bernard (1496), 7.4, De pollutione nocturna, fol. 205vb. I am in the process of studying this material as part of my larger project on medieval medicine and sleep.


See Elliott (1999), chap. 1 and the earlier note about my future work on this topic. In many ways, nocturnal pollution was very similar to sleepwalking, although the sources never link the two. In part this is due to the medical literature’s general organisation of diseases from head to toe: sleepwalking was a disease of the head, while nocturnal pollution was seen as a disease of the genitals.


Bernard (1496), fol. 68ra: ‘multa somnia et fantasmata videre sine capite et caude… ideo ex hoc sumus secundum Aui vj de naturalibus in continuo cruciatu.’ The passage is derived loosely from Aristotle’s De anima, 4.2, dealing with the virtus imaginativa. See Avicenna (1968), pp. 20–22.


This passage has parallels to Aristotle’s treatise on dreams. For the medieval Latin translations, see Drossaart Lulofs (1947).


Bernard (1496), fol. 68a: et multa somnia et fantasmata videre sine capite et caude. The final phrase could equally in a less literal translation suggest that the number of the phantasms is endless, without beginning (head) or end (tail).


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