 In Western Philosophy, the earliest discussions of dualist ideas are in the writings of Plato who maintained that humans' "intelligence" (a faculty of the mind or soul) could not be identified with, or explained in terms of, their physical body. However, the best-known version of dualism is due to René Descartes (1641), and holds that the mind is a non-extended, non-physical substance, a "res cogitans". Descartes was the first to clearly identify the mind with consciousness and self-awareness, and to distinguish this from the brain, which was the seat of intelligence. He was therefore the first to formulate the mind – body problem in the form in which it still exists today.
