The theory of living beings as machines of nature and the conception of composite substances endowed with conjoined souls, entelechies, or monads, as well as that of organic bodies, were solidified over the course of the transformations of Leibniz's thought that issued in the New System of Nature. On this basis, the monadological versions of a system of nature centered upon the integrated organization ad infinitum of living beings were gradually articulated. Leibniz aimed to spell out a science, or physiology of vital processes, that would be, as much as possible, in agreement with the epistemological exigencies of the complex metaphysical model that he had elaborated. On the one hand, Leibniz offers a critical evaluation of the methodological options that divide the allegiances of the physicians and naturalists who are his contemporaries; what is more, he determines the profile of the analyses and explications that are to be promoted. For This double preoccupation translates into the scientific exchanges and correspondences that accompany the construction of the theory of organic bodies as constituents of machines of nature. The author focuses on the particular case of the propositions concerning the science of the living that stem from his reaction to the work of Georg Ernst Stahl.
