My aim is to question the different finalistic approaches to the human body that underlie the theological justifications of anatomy. To do so, I analyze the references that Leibniz made to Galen’s "On the Use of the Parts" that had a strategic purpose in his campaign against materialism. I show that the new mechanistic conception that is endorsed by Leibniz leads him to contradict Galen’s method on two key aspects: 1/ the principle of the best, which, according to Leibniz, is grounded in God’s rationality, casts doubt on the Galenic taxonomy of the human body and precludes the identification of a biological function with the final cause of an organ; 2/ the infinite complexity of Leibniz’s ‘machines of nature’, i.e. living bodies, conflicts with the anthropomorphic representation of their creation as the molding of unformed materials. Accordingly, Leibniz agrees with Galen that a Creator did his best in making our bodies, but he disagrees profoundly on the exact implications of this very general claim.