Contemporary debates on the status of animals -- Epic and pre-Socratic thought -- Aristotle and the Stoics : the evolution of a cosmic principle -- Classical defenses of animals : Plutarch and Porphyry -- The status of animals in medieval Christianity -- Descartes on the moral status of animals -- The empiricists, the utilitarians, and Kant -- Conceptions of continuity in the nineteenth and early twentieth centuries : Schopenhauer, Darwin, and Schweitzer -- Postmodern conceptions of the human-animal boundary -- Rethinking the moral status of animals.