Phrenitis is ubiquitous in ancient medicine and philosophy. Galen mentions the disease innumerable times, patristic authors take it as a favourite allegory of human flaws, and no ancient doctor fails to diagnose it and attempt its cure. Yet the nature of this once famous disease has not been understood properly by scholars. This book provides the first full history of phrenitis. In doing so, it surveys ancient ideas about the interactions between body and soul, both in health and in disease. It also addresses ancient ideas about bodily health, mental soundness and moral 'goodness', and their heritage in contemporary psychiatric ideas. Readers will encounter an exciting narrative about health, illness and care as embedded in ancient 'life', but will also be forced to reflect critically on our contemporary ideas of what it means to be 'insane'. This title is also available as open access on Cambridge Core.