Responding to henry Oldenburg’s request to clarify his views about the relation between God and Nature (Ep71), Spinoza writes: “I favor an opinion concerning God and Nature far different from the one Modern Christians usually defend. For I maintain that God is, as they say, the immanent, but not the transitive, cause of all things” (Ep73, iv/307). In the Ethics, Spinoza does not define the notion of causa immanens, but we can easily retrieve the precise meaning of the term by scrutinizing E1p18d in which Spinoza proves that “God is the immanent, not the transitive, cause of all things [Deus est omnium rerum causa immanens; non vero transiens].”