This essay locates itself in the whereabouts of the following thesis: the post-structuralist reading of psychoanalysis, as developed specially by Gilles Deleuze, might be based on a particular reading of Spinoza’s God as infinite substance. Everything stems, thus, from the definition that appears in sixth place in the Ethics: «By God, I understand Being absolutely infinite, that is to say, substance consisting of infinite attributes, each one of which expresses eternal and infinite essence» (E, I, Def. 6).3 To which, one must add the accompanying «Explanation: I say absolutely infinite but not infinite in its own kind (in suo genere); for of whatever is infinite only in its own kind, we can deny infinite attributes; but to the essence of that which is absolutely infinite pertains whatever expresses essence and involves no negation». This is the definition of what I shall call the ontological structure, the key concept of which is infinity. As I see it, at the nucleus of Spinoza’s philosophy,