动物志
In the "History of Animals", Aristotle sets out to investigate the existing facts (Greek "hoti", what), prior to establishing their causes (Greek "dioti", why). The book is thus a defence of his method of investigating zoology. Aristotle investigates four types of differences between animals: differences in particular body parts (Books I to IV); differences in ways of life and types of activity (Books V, VI, VII and IX); and differences in specific characters (Book VIII).