Aristotle (Greek, 384–322 B.C.) was a disciple of Plato erroneously believed that the heart is the source of all mental processes.
Aristotle argued that because the brain is bloodless, it fills the function of a "radiator," cooling hot blood ascending from the heart. Aristotle believed sensory experience to be the basis of all knowledge, although the five (5) senses and the common sense provided only the information from which knowledge could be derived. Aristotle also believed that everything in nature had within it an entelechy (purpose) that determined its potential. Active reason, which was considered the immortal part of the human soul, provided humans with their greatest potential, and therefore fully actualized humans engage in active reason. Because everything was thought to have a cause, Aristotle postulated an unmoved mover that caused everything in the world but was not itself caused.