Abstract
This is a truly outstanding contribution to contemporary scholarship on Leibniz’s methodology and natural philosophy. By providing the original edition of Leibnizian manuscripts dating back to the period 1676-1680, in particular the De corporum concursu, Michel Fichant has confirmed what some previous scholars had surmised—that Leibniz had substituted his new principle of conservation of vis viva for the Cartesian principle of conservation of quantity of motion measured by mv shortly after his return from France, and quite a few years before the publication of the Brevis demonstratio erroris memorabilis Cartesii in the Acta Eruditorum. Fichant has conclusively shown that the turning point rightly occurs in the midst of Leibniz’s writing the De corporum concursu in January-February 1678. At the time, Leibniz was groping for a coherent system of physical and mathematical reasons to ground the mechanical laws of motion beyond the relativistic formulas which Huygens, Wallis, and Wren had provided in response to the enquiry launched by the Royal Society in 1668.