From a Metaphysical to a Scientific Object: Mechanizing Light in Galilean Science
Ancient philosophers generally offered three lines of thought for conceiving of light. Classical atomism took light to be a material emission of small and swift particles; Plato spoke about light as a phenomenon charged with metaphysical tones; and Aristotle, who surprisingly only spoke of light in two brief passages in his entire corpus, asserted that light was not a substance but a quality of the medium. During the Middle Ages phenomena related to light were studied mathematically by geometrical optics, though it is well known that the mathematical approach was not, strictly speaking, a part of natural philosophy. The nature of light in that period was only studied—with few exceptions—by authors who expressed conceptions of nature that were closer to Neoplatonic cosmologies. In most cases, the study of light was nearer to metaphysics than to natural philosophy.