Ren? Descartes' illustration of dualism. Inputs are passed on by the sensory organs to the epiphysis in the brain and from there to the immaterial spirit. In philosophy of mind, dualism is a set of views about the relationship between mind and matter, which begins with the claim that mental phenomena are, in some respects, non-physical.[1] Ideas on mind/body dualism originate at least as far back as Zarathushtra. Plato and Aristotle deal with speculations as to the existence of an incorporeal soul which bore the faculties of intelligence and wisdom. They maintained, for different reasons, that people's "intelligence" (a faculty of the mind or soul) could not be identified with, or explained in terms of, their physical body.[2][3] A generally well known version of dualism is attributed to Ren? Descartes (1641), which holds that the mind is a nonphysical substance. 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. Hence, he was the first to formulate the mind-body problem in the form in which it exists today.[4] Dualism is contrasted with various kinds of monism, including physicalism and phenomenalism. Substance dualism is contrasted with all forms of materialism, but property dualism may be considered a form of emergent materialism and thus would only be contrasted with non-emergent materialism.[5] This article discusses the various forms of dualism and the arguments which have been made both for and against this thesis.