 To be sure, his convictions regarding living matter (or all of matter inasmuch as it is potentially living and sensing) are tied to his admiration for the metaphysics of a single substance composed of an infinite number of modes. As he states in the Rêve de D’Alembert, “There is only one substance in the universe” (DPV XVII, 107; Wartofsky 1952/1979, Deprun 1986, Bourdin 2008). But nowhere does Spinoza seek to connect his metaphysics to the life sciences; even if the notion of the conatus was frequently taken up in the generations after him to mean something like a survival impulse in living beings, this was not what he meant at all. Diderot is grafting “vitalist” elements onto a substance metaphysics, or at least, he is connecting an apparently empirical account of the self-organisation of matter with a new metaphysics. Epigenesis is not just one biological theory among others here, but rather, part of a revised metaphysics of matter, which Diderot presents in more overtly ideological terms in the Rêve: