I argue that the prime matter that Leibniz posits in every created monad is understood by him to be a mere defect or negation, and not something real and positive. Further, I argue that Leibniz’s talk of prime matter in every created monad is inspired by the thirteenth-century doctrine of spiritual matter, but that such talk is simply one way in which Leibniz frames a point that he frequently makes elsewhere—namely, that each creaturely essence incorporates a limitation that is the (...) ultimate source of an original imperfection that affects the creature from the first moment of its existence. (shrink)