This book began with an expression of astonishment. At the beginning of the nineteenth century, and possibly earlier, a certain distinction between natural philosophy and natural science was unmistakable. The contemptuous reactions of Goethe's contemporaries to his theory of color and the growing opposition that Schelling's and Hegel's Naturphilosophie met with in Germany after 1830 were symptoms of the autonomy that natural science had achieved, which entailed that research in natural science should be evaluated using inherent norms.² This growing separation was already apparent in mechanics, as has been shown in the last two chapters. At one extreme we have the essay competition concerning the foundation of force, which the speculative philosophy department of the Berlin Academy made so bold as to announce in 1779, and which was already the target of merciless derision at that time, from most of the practitioners of mechanics. On the other extreme stands Lagrange's classical work on analytic mechanics, which was marked by the absence of considerations from natural philosophy.