D O C U M E N T 5 0 3 N E W T O N ’ S M E C H A N I C S 4 9 3 503. “Newton’s Mechanics and Its Influence on the Shaping of Theoretical Physics”[1] [Einstein 1927k] Published 25 March 1927 In: Die Naturwissenschaften 15 (1927): 273–276. The two-hundredth anniversary of the death of Newton falls at this time. One’s thoughts cannot but turn to this shining spirit, who pointed out, as none before or after him did, the path of Western thought and research and practical construction. He was not only an inventor of genius in respect of particular guiding methods he also showed a unique mastery of the empirical material known in his time, and he was marvelously inventive in special mathematical and physical demonstrations. For all these reasons he deserves our deep veneration. He is, however, a yet more significant figure than his own mastery makes him, since he was placed by fate at a turning-point in the world’s intellectual development. This is brought home viv- idly to us when we recall that before Newton there was no comprehensive system of physical causality which could in any way render the deeper characters of the world of concrete experience. The great materialists of ancient Greek civilization had indeed postulated the reference of all material phenomena to a process of atomic movements controlled by rigid laws, without appealing to the will of living creatures as an independent cause.[2] Descartes, in his own fashion, had revived this ultimate conception. But it remained a bold postulate, the problematic ideal of a school of philosophy. In the way of actual justification of our confidence in the existence of an entirely physical causality, virtually nothing had been achieved before Newton. Newton’s aim was to find an answer to the question: Does there exist a simple rule by which the motion of the heavenly bodies of our planetary system can be completely calculated, if the state of motion of all these bodies at a single moment is known? Kepler’s empirical laws of the motion of the planets, based on Tycho Brahe’s observations, were already enunciated and demanded an interpretation.1) 1) Everyone knows today what gigantic efforts were needed to discover these laws from the em- pirically ascertained orbits of the planets. But few reflect on the genius of the method by which Kepler ascertained the true orbits from the apparent ones—i.e., their directions as observed from the earth. [p. 273]