Book excerpt: This work investigates how ancient philosophers understood productive knowledge or technê and used it to explain ethics, rhetoric, politics and cosmology. In eleven chapters leading scholars set out the ancient debates about technê from the Presocratic and Hippocratic writers, through Plato and Aristotle and the Hellenistic age (Stoics, Epicureans and Sceptics), ending in the Neoplatonism of Plotinus and Proclus. Amongst the many themes that come into focus are: the model status of ancient medicine in defining the political art, the similarities between the Platonic and Aristotelian conceptions of technê, the use of technê as a paradigm for virtue and practical rationality, technê ́s determining role in Platonic conceptions of cosmology, technê ́s relationship to experience and theoretical knowledge, virtue as an 'art of living', the adaptability of the criteria of technê to suit different skills, including philosophy itself, the use in productive knowledge of models, deliberation, conjecture and imagination.