A vigorous polemicist as well as a rational philosopher, Aristotle (384 - 322 BCE) has the task in his ethics of demonstrating how men become good and why happiness can, and should, be our goal. The success of Aristotle's endeavour may be measured by the enormous impact of his ethics on Western moral philosophy through the centuries. Composed as mere lecture notes, it possesses a startling boldness and represents an exacting, exciting challenge to the reader. By converting ethics from a theoretical to a practical science, and by introducing psychology into his study of behaviour, Aristotle both widens the field of moral philosophy and simultaneously makes it more accessible to anyone who seeks an understanding of human nature.