Abstract

The "Tentamen de motuum coelestium causis" (1688), the only physico- mechanical essay published by Leibniz on the eve of his trip to Rome, has been closely studied in recent years as a tentative theory of planetary motions, alternative to Newton's attraction theory in the "Principia" (1687). By reviewing the various comments, the present paper stresses Leibniz's strategy towards the Holy Seat to promote both his anti-newtonian celestial dynamics and the rehabilitation of Galileo and Copernicus in the eyes of Roman Catholic learned opinion. Between the opposite metaphysical implications of the theory of matter and the calculus, «materialism» - a neologism linked to the new «mechanical philosophy» - was the most dramatic stroke reciprocally exchanged by Newton and Leibniz in their last epistolary quarrel.