For the Pre-Socratic philosophers the soul was the source of movement and sensation, while for Plato it was the seat of being, metaphysically distinct from the body that it was forced temporarily to inhabit. Plato's student Aristotle was determined to test the truth of both these beliefs against the emerging sciences of logic and biology. His examination of the huge variety of living organisms - the enormous range of their behaviour, their powers and their perceptual sophistication - convinced him of the inadequacy both of a materialist reduction and of a Platonic sublimation of the soul. In De Anima, he sought to set out his theory of the soul as the ultimate reality of embodied form and produced both a masterpiece of philosophical insight and a psychology of perennially fascinating subtlety.
Aristotle was born in 384BC. For twenty years he studied at Athens at the Academy of Plato, on whose death in 347 he left, and some time later became tutor to Alexander the Great. On Alexander's succession to the throne of Macedonia in 336, Aristotle returned to Athens and established his school and research institute, the Lyceum. After Alexander's death he was driven out of Athens and feld to Chalcis in Euboea where he died in 322. His writings profoundly affected the whole course of ancient and medieval philosophy. HUGH LAWSON-TANCRED was born in 1955 and educated at Eton and Balliol College, Oxford. He is a Departmental Fellow in the Department of Philosophy at Birkbeck College in the University of London. He has published extensively on Aristotle and Plato and is currently engaged in research in computational linguistics. He translates widely from the Slavonic and Scandinavian languages. His translations of Aristotle's The Art of Rhetoric and De Anima are also published in Penguin Classics. He is married with a daughter and two sons and lives in North London and Somerset.