In a major contribution to the theory of perception, A. D. Smith presents a truly original defense of direct realism--the view that in perception we are directly aware of things in the physical world. The Problem of Perception offers two arguments against direct realism--one concerning illusion, and one concerning hallucination--that no current theory of perception can adequately rebut. Smith then develops a theory of perception that does succeed in answering these arguments; and because these arguments are the only two that present direct realism with serious problems arising from the nature of perception, direct realism emerges here for the first time as an ultimately tenable position within the philosophy of perception. At the heart of Smith's theory is a new way of drawing the distinction between perception and sensation, along with an unusual treatment of the nature of objects of hallucination. With in-depth reference to both the analytical and the phenomenological literature on perception, and with telling criticism of alternative views, Smith's groundbreaking work will be of value to philosophers of perception in both the analytical and the phenomenological tradition, as well as to psychologists of perception.