Galileo Galilei (1564-1642) is, according to Albert Einstein and Steven Hawking, the father of modern physics and of modern science in general. It is well known that the Italian physicist invented a new theory of motion and that in 1633 he was condemned by the Roman Church for his defence of a heliocentric universe. However, this seminar will focus on an aspect which is less well documented in the literature despite its historical importance.
Galileo observed with his new telescope the craters of the Moon, the satellites of Jupiter and the phases of Venus, which gave empirical support to the heliocentric model of the universe. These astronomical observations would ultimately lead to the collapse of the Ptolemaic/Aristotelian geocentric system which had dominated our worldview for a very long time. The ‘Big Stargazer’, as Robert Boyle called him, documented his astronomical observations in his bestseller, Sidereus nuncius (1610) and his Letters on Sunspots (1612-13) so that his views were spread far beyond the borders of Western Europe. However, it is not as well-known that Galileo adopted his new telescope around 1609 to look at small things from nearby. In 1624, Galileo gave his microscope (occhiolino) to the founder of the Accademia dei Lincei whose members used it to make drawings of plants, fungi and flowers. The Lincean Giovanni Faber named this optical device with one convex and one concave lens a ‘microscopio’.
Firstly, this seminar will show how Galileo introduced in two books – both published by the Accademia dei Lincei – a new conception of qualities of the body. Indeed, Galileo makes in his Assayer (1623) [Il Saggiatore] a distinction between the so-called primary qualities (that bodies-in-themselves have) such as size and motion, and secondary qualities such as colours, savours and odours (that are extrinsic qualities which are attributes to bodies). Furthermore, this talk argues that Galileo had given already a first version of the distinction in his second Letter on Sunspots. Moreover, it will be shown that this distinction is already found even in Sidereus nuncius. This talk will not only focus on the text fragments from Galileo and the members of his circle, but also on the pictures of astronomical and microscopic observations that they made and included in their publications.
Finally, this seminar will demonstrate the historical importance of Galileo’s conception of qualities of the body, arguing that Galileo’s concept was transmitted via the work of E. Kant (1724-1804), J. Müller (1801-1858) and H. van Helmholtz (1821-1894) into contemporary sensory physiology. Consequently, Galileo’s views has influenced our conception of bodies.
