Galileo and the senses: "Sensory physiology" and "visual psychophysics" in the work of Galileo Galilei
Marco PICCOLINO1 and Nicholas J. WADE2
In spite of the great interest among historians of science in Galileo’s work at the dawning of modern science, there have been relatively few studies concerned with his reflections on sensory physiology. This has occurred even though Galileo’s great perceptiveness in interpreting the astronomical images obtained with his telescope depended to a large extent on these reflections. Galileo’s interest in the physiology of the senses, and particularly of vision and hearing, is explicitly documented in a letter written in 1610 to the secretary of the Grand Duke of Tuscany; in it he spoke of his plan to write a book entitled De visu et coloribus and another entitled De sono et voce. Although these books were never published (and probably never written), the senses and perception feature in many of Galileo’s letters and published works. For example, in the Saggiatore (1623), there are some well-known passages concerned with the so-called “primary” and “secondary qualities”: Galileo seemed to anticipate the epistemological and physiological approaches to sensory mechanisms that we associate with modern studies. As a founder of the scientific method, Galileo pointed out the importance of both experimentation and direct observation of the “book of the universe” as a better source of scientific truth than the “books of men”. However, at the same time he had clear grasp of the fact that senses are adapted to the basic needs of life and are not by themselves a sure path to scientific knowledge of the world. This is particularly evident in his interpretation of structures on the moon’s surface and of “secondary light” of the moon, of the appearance of Venus, of his study of sunspots, and of the visibility of “fixed stars” (where Galileo’s science reaches some of its highest points). We examine the foundations upon which Galileo built his perceptive sensory physiology and how it was embedded in his published and unpublished texts.
Session IX. Italian Heritage and the Galvani-Volta Controversy
Pavia, Italy, 2006