Aristotelianism remained the dominant influence on the course of natural philosophy taught at the University of Paris until the 1690s, when it was swiftly replaced by Cartesianism. The change was not one wanted by church or state and can only be understood by developments within the wider University. On the one hand, the opening of a new college, the Colle`ge de Mazarin, provided an environment in which the mechanical philosophy could flourish. On the other, divisions within the French Catholic Church between Augustinians and Molinists led to Cartesianism finding support within an important section of the faculty of theology, which was the traditional guardian of philosophical orthodoxy. The conversion of the University of Paris to Cartesianism had important consequences. It encouraged similar changes to the natural philosophical curriculum throughout France and affected the structure and raison d'eˆtre of the Acade´mie des Sciences.As in the late middle ages, the science of physics in 17th-and 18th-century France was normally taught as one part of a quadripartite course of philosophy. In contrast to the earlier period, however, institutionalized philosophy teaching after 1600 was no longer provided by a university faculty of arts. Instead, the subject was taught in one of 150 colle`ges de plein exercice. These were schools established in most of the large towns of France in the course of the sixteenth century to offer tuition in the Latin and Greek humanities, a new field of study promoted all over Europe by Renaissance humanists to replace traditional propaedeutic courses in Latin grammar. Over time, in France if not usually elsewhere, these new schools added to their remit the task of teaching philosophy, which was studied once the humanities course had been completed, and the faculties of arts became simply examining boards. Some of the schools were located in the old residential colleges of France's sixteen universities but most were new. Most, too, whatever had been the case in the sixteenth century, ended up by being taken over by the regular orders, especially the Jesuits. The only large block of colle`ges de plein exercice outside the regulars' control were the ten attached to the University of Paris, historically the most important centre of philosophy teaching in Latin Christendom. The philosophy course in all these colle`ges de plein exercice was always two years in length. Students would begin by studying logic and ethics, then proceed to physics and metaphysics, though increasingly from 1650 natural philosophy would be taught last and take up Science & Education (2006) 15:259-278 Ó Springer 2006