Spinoza's remarks about consciousness in the Ethics constitute two theories about conscious experience and knowledge. Several remarks, including 3p9 and 4p8, make the point that self knowledge—an especially valuable good for Spinoza—is not available to introspection. We are, as a matter of course, conscious of ourselves, but we do not, as a matter of course, know ourselves. A second group of remarks, all of which occur in part 5 of the Ethics, emphasizes a different point about consciousness and knowledge: the knowledge that distinguishes the minds of the most powerful or virtuous people is conscious. The characterization of human consciousness that underlies both theories is best understood as one on which a wide variety of ideas in human minds are conscious, and the intensity or degree of consciousness of a given idea is a function of its power. For human minds, because the power of any idea derives from the power of its causes and because many ideas have external causes, there are no grounds for taking the intensity of conscious experience to track a mind's power closely. Rather, as the second group of remarks suggests, power in a human mind tracks the degree to which knowledge characterizes a mind's conscious states.