This first extensive study of Spinoza's philosophy of mind concentrates on two problems crucial to the philosopher's thoughts on the matter: the requirements for having a thought about a particular object, and the problem of the mind's relation to the body. Della Rocca contends that Spinoza's positions are systematically connected with each other and with a principle at the heart of his metaphysical system: his denial of causal or explanatory relations between the mental and the physical. In this way, Della Rocca's exploration of these two problems provides a new and illuminating perspective on Spinoza's philosophy as a system.