 We know our own self, Mill claims, only as it phenomenally appears to us—and we know of other selves only by inference from our own case. Mill rejects the “common theory of Mind, as a so-called substance” (Examination, IX: 206). But he also resists the total reduction of mind to the existence of sensations—or even to the existence of possible sensations—on the grounds that there remains a unity to apperception. As he points out, a reduction of self to sensations cannot be wholly satisfactory, because a sense of the self enters into many sensations as a constituent part. When I recall a memory, for instance, the sensation is of a memory which has as part of its content that it is my memory. 