Inspection of surviving mirrors and related objects shows that they were too crude to offer the early Renaissance painter an optical short-cut to a naturalistic image of his subject. The craftsmanship of mirror makers was independent of and inferior to the quality of theories of image formation of the day.

This paper deals with Hobbes's theory of optical images, developed in his optical magnum opus, ‘A Minute or First Draught of the Optiques’, and published in abridged version in De homine. The paper suggests that Hobbes's theory of vision and images serves him to ground his philosophy of man on his philosophy of body. Furthermore, since this part of Hobbes's work on optics is the most thoroughly geometrical, it reveals a good deal about the role of mathematics in Hobbes's philosophy. (...) The paper points to some difficulties in the thesis of Shapin and Schaffer, who presented geometry as a ‘paradigm’ for Hobbes's natural philosophy. It will be argued here that Hobbes's application of geometry to optics was dictated by his metaphysical and epistemological principles, not by a blind belief in the power of geometry. Geometry supported causal explanation, and assisted reason in making sense of appearances by helping the philosopher understand the relationships between the world outside us and the images it produces in us. Finally the paper broadly suggests how Hobbes's theory of images may have triggered, by negative example, the flourishing of geometrical optics in Restoration England. (shrink)

: Marin Mersenne was central to the new mathematical approach to nature in Paris in the 1630s and 1640s. Intellectually, he was one of the most enthusiastic practitioners of that program, and published a number of influential books in those important decades. But Mersenne started his career in a rather different way. In the early 1620s, Mersenne was known in Paris primarily as a writer on religious topics, and a staunch defender of Aristotle against attacks by those who would replace (...) him by a new philosophy. In this essay, I would like to examine Mersenne's changing attitude toward Galileo. In the early 1620s, Mersenne lists Galileo among the innovators in natural philosophy whose views should be rejected. However, by the early 1630s, less than a decade later, Mersenne has become one of Galileo's most ardent supporters. How, then, did Mersenne learn to love Galileo? (shrink)

Longtemps eclipse, Mersenne est cependant un personnage eminemment representatif de la pensee du public instruit de son temps, celle qui quitte la scolastique pour le mecanisme. Mersenne s'illustre comme le secretaire de l'Europe savante, en servant d'intermediaire entre les chercheurs. Depuis le rationalisme cartesien jusqu'au sensualisme de Hobbes, l'eclectisme de Mersenne est plus des plus instructifs. C'est pourquoi la part qu'il a prise dans le grand travail collectif d'ou sortit la philosophie nouvelle meritait d'etre tiree d'un injuste oubli. Robert Lenoble (...) rappelle ainsi que le mecanisme, loin de s'epuiser dans le cartesianisme, jaillit de sources diverses, au confluent desquelles se trouve Mersenne. (shrink)