In De Partibus Animalium I Aristotle sets out his philosophy of biology, discussing cause, necessity, soul, genus, and species, definition by logical division, and general methodology. In De Generatione Animalium I he applies his hylomorphic philosophy to the problem of animal reproduction. The translation is close, and includes passages from De Generatione Animalium II which complete Aristotle's theory of reproduction. The notes interpret Aristotle's arguments and discuss his views on major issues such as natural teleology.