 The question of the existence of the atom had divided philosophy and natural science against one another. The philosophers held that atoms are only a fiction or hypostasis, while the physicists claimed that they are a reality, the best inference from observation and experiment, even though they are unobservable themselves. This disagreement among philosophers and scientists reflected their wider disagreements about the nature of matter and scientific method. They were opposed on three fronts. First, the philosophers held that matter is infinitely divisible and continuous, while the scientists maintained that it is indivisible and discrete. Second, the philosophers made forces fundamental, analyzing matter into powers of attraction and repulsion; the scientists, however, made matter the basis of force, claiming that forces inhere in matter and that they are only a way of accounting for its law-like regularities. Third, the philosophers stated that the fundamental questions about nature cannot be settled by observation and experiment and have to be determined a priori; the physicists insisted that every question of natural science has to be determined by observation and experiment and that questions about its very possibility are not the concern of natural science. The chief philosophers, who were all Germans, were Schelling, Hegel and Herbart; their philosophy of nature was in the tradition of Kant’s Metaphysische Anfangsgründe der Naturwissenschaften. The main scientists, who were French, were one and all experimental physicists, men like André Ampère (1775–1836), Augustin Cauchy (1858–1898) and Augustin Fresnel (1788–1827).