strong...the more honourable animals have been allotted a more honourable soul...strong pWhat is the nature of the soul It is this question that Aristotle sought to answer in emDe Animaem emOn the Soulem. In doing so he offers a psychological theory that encompasses not only human beings but all living beings. Its basic thesis, that the soul is the form of an organic body, sets it in sharp contrast with both Pre-Socratic physicalism and Platonic dualism. emOn the Soulem contains Aristotle's definition of the soul, and his explanations of nutrition, perception, cognition, and animal self-motion. pThe general theory in emDe Animaem is augmented in the shorter works of emParva Naturaliaem, which deal with perception, memory and recollection, sleep and dreams, longevity, life-cycles, and psycho-physiology. pThis new translation brings together all of Aristotle's extant and complementary psychological works, and adds as a supplement ancient testimony concerning his lost writings dealing wit