Besides the reflectance profiles, light waves, retinal changes, neural events, and behavioral responses reviewed in Chapter 1, normal cases in which a person sees a red apple will involve the apple's looking red to that person. An apple's looking red requires a distinctive kind of conscious occurrence – a red experience – that is something in its own right, and not reducible to behavioral responses, or dispositions to behavioral responses, or brain state bases of such dispositions. Experiences are caused by neural events, but are not identical to or reducible to them or to any other material events. Experiences are constituted by phenomenal qualities; indeed, phenomenal qualities occur only in experiences and are the essence of consciousness in the most fundamental sense of that term.