 Spinoza’s epistemology and philosophy of mind are governed by some rather unintuitive commitments: first, a commitment to universal intelligibility, often described as Spinoza’s version of what, with Leibniz, came to be known as the Principle of Sufficient Reason (PSR); second, a commitment to the explanatory closure of the mental and the physical; third, a commitment to the explanatory and ontological priority of an infinite thinker over any finite mind. The entry discusses these commitments before diving into the details of Spinoza’s theories of cognition and mindedness. (In line with Spinoza’s own practice, what follows treats “conceive”, “understand”, “think”, “explain”, and “cognize” as roughly interchangeable [cf. Wilson 1999: ch.10; Della Rocca 1996].)