Anne-Lise Rey’s account of Maupertuis’s physical theology challenges the efforts on the part of commentators to align his work with Newton, Leibniz, or critics of Leibniz by examining the innovative epistemological principles that inform his Essay on Cosmology (1750). Through an analysis of his proofs of the existence of God in this work, she investigates Maupertuis’s view on how we can obtain certain knowledge of nature and the place he affords to experimentation and contingency in this regard. Rey claims that Maupertuis, despite his hostility toward Descartes, Leibniz, and Wolff, did not abolish the idea of a metaphysics of nature per se, but tried to strike a new balance between, on the one hand, the deduction of laws from the nature of bodies and, on the other hand, experimentation. More specifically, she argues that Maupertuis in the Essay on Cosmology affirms our epistemic incapacity to grasp the whole system of nature and, hence, argues that the probable truths we can obtain in physics by means of experiments are superior to the geometrical truths that Descartes and his followers aimed to establish in both physics and metaphysics.