This paper enquires about Aristotle's treatment of body sense; by 'body sense' is meant cognition of the state of our bodies, such items as itches, chills, hunger, cramps etc. At first it seems that Aristotle takes very little account them, and even fails to realize that – just as he has provided an account of perception of external objects – he owes us an account of this province of consciousness as well. An examination, however, of a remarkable thought-experiment in the de Anima allows us to unearth one of its presuppositions: it turns out that Aristotle must take body sense to be a primitive of explanation. Any animal, just by being an animal, is aware of its body states. This leads to a deeply revised understanding of what it is that Aristotle is trying to do in explaining sense perception – a revised understanding that absolves him of the common criticism that he fails adequately to tackle, or even to attempt, or even to notice, the mind-body problem.