It is useful to distinguish three senses of the word 'consciousness'. 'Minimal' consciousness is the occurrence of any mental activity, whether or not the subject is aware of this activity. 'Perceptual' consciousness is perceptual activity. Minimal and perceptual consciousness may be present, yet 'introspective' consciousness be lacking. Introspective consciousness is conceived as it was by Locke and Kant: as perception-like awareness of the subject's own current mental states and activities. It includes introspective consciousness of introspective consciousness itself. A useful model for demystifying and naturalizing introspective consciousness is the subject's proprioceptive awareness of bodily states and activities. Introspective consciousness may be further subdivided into 'reflex' introspective consciousness and 'introspection proper'. The distinction is one of degree: the degree of attention involved. We attach a quite special importance to introspective consciousness and are particularly unwilling to identify it with a purely physical process in the brain. It is suggested, however, that this springs from (a) the fact that what is introspected is taken to be a state or activity of a single thing, the self; and (b) the fact that event-memory is generally only possible if the event remembered was the object of introspective consciousness at the time. Without introspective consciousness, therefore, awareness of a self and the past history of that self is lacking.