How does the law regard and define mental incompetence, when faced with the problem of meting out justice? To what extent has the law relied on extra-legal authorities - be they religious or scientific - to frame its own categories of mental incompetence and madness? Wild Beasts and Idle Humours takes us on a journey through the changing historical landscape of human nature and offers an unprecedented look at the legal conceptions of insanity from the pre-classical Greek world to the present. Although actual trial records are either totally lacking or incomplete until the 18th century, there are other sources from which the insanity defenses can be constructed. In this book Daniel Robinson, an historian of psychology, pores over centuries of written law, statements by legal commentators, summaries of crimes, and punishments, to glean from these sources an understanding of epochal views of responsibility and competence. From the Greek phrenesis to the Roman notions of furiosus and non compus mentis, from the 17th-century witch trials to today's interpretation of mens rea, Robinson take us through history and provides the story of how the insanity defence has been construed as a meeting point of the law and those professions that chart human behaviour and conduct: namely religion, medicine and psychology. The result is an historical account of insanity within western civilization. Wild Beasts and Idle Humours should be for anyone interested in the evolution of thinking not merely about legal insanity but about such core concepts as responsibility, fitness for the rule of law, competence to enter into contracts and convenants, the role of punishments, and the place of experts within the overall juridical context.