While both intuitive knowledge (scientia intuitiva) and reason (ratio) are adequate ways of knowing for Spinoza, they are not equal. Intuitive knowledge, which Spinoza describes as the ‘greatest virtue of mind’, is superior to reason. The nature of this superiority has been the subject of some controversy due to Spinoza's notoriously parsimonious treatment of the distinction between reason and intuitive knowledge in the Ethics. In this paper, I argue that intuitive knowledge differs from reason not only in terms of its method of cognition—but also in terms of its content. More specifically, I maintain that there is something that is known by intuition, namely the unique essences of things, that is not known by reason. My argument is supported by an examination of Spinoza's account of essences in the Ethics, which reveals that he is committed to both unique and shared essences. Based on this dual commitment, I argue that whereas for Spinoza both reason and intuition can be said to reach adequate knowledge of the shared essence of a thing, the unique essence of a singular thing, which is nothing but its actual essence, can only be known through intuitive knowledge.