The Mathematical Theses Defended at collège de Clermont (1637-1682): How to Guard a Fortress in Times of War

Abstract : To capture some of the early modern teaching practices while studying the interaction between ancient and new doctrines, this chapter focuses on the thesis booklets defended at the Jesuit collège de Clermont from 1637 to 1682. First, it examines what this exceptional corpus (almost one thesis in mathematics per year is available) reveals about the role that the Parisian Jesuits assigned to the defense of mathematical theses in the context of their complex relationship with the University of Paris. Then, it focuses on the optics theses that were defended under Pierre Bourdin: they borrowed from the Jesuit theoretical optics of the 1610-1620s, while making room for extraordinary devices such as the Specillum Fidei. Finally, it shows that the optics of Ignace-Gaston Pardies, who held the chair of mathematics some twenty years later, incorporated the main lesson of the novatores: it is not a theory of vision, but a theory of light, which is based on mechanics defined as the science of motion in general. While Bourdin preserved the structure of Aristotelian knowledge, Pardies overturned this structure by considering mechanics as the key to all physics.