This book deals with some Aristotelian philosophers of the Hellenistic Age, ranging from Theophrastus of Eresus to Cratippus of Pergamum. The problem of knowledge, the question of time, and the doctrine of the soul are investigated by comparing these Peripatetics' views with Aristotle's philosophy, and above all by setting their doctrines within the broader framework of post-Aristotelian and Hellenistic philosophies (the Old Academy, Epicureanism, and Stoicism).