The idea of consciousness which the modern scientific psychologist appeals to has its roots partly in the empirical and rational rejections of Aristotelian hylomorphic theory and partly in the rejection of the Kantian synthesis of empiricism and rationalism. Dualistic assumptions are clearly operating in the separation of consciousness from the world it is conscious of. Both Plato and Descartes were dualists, the latter being a disguised materialist who claimed the mind and the body meet in the physical organ of the brain, the former being committed to a soul that could detach itself from a physical body in a manner that is absolutely mysterious. In both cases the division of the physical world from consciousness is irrevocable. Both Aristotle and Kant avoided the pitfalls of dualism and its half brother materialism and it is not a simple matter to see how to parse their thoughts into the language of consciousness. The work of Freud, paradoxically appears to offer the best account of consciousness as a realm extending over the operating domains of three principles, the energy regulation that is responsible for our waking states, the pleasure-pain principle which is responsible for pleasurable and painful modifications of consciousness and the reality principle which Freud claims is occupied with the real problems of love and work.