Astrology and the Moon have featured within concepts of madness and mental wellbeing since ancient times, as the word ‘lunacy’ would suggest. This talk focuses on the autobiographical writings of John Thomas Perceval (1803–1876), an English asylum patient (and son of the British Prime Minister, Spencer Perceval) who, after his release from confinement, co-founded an advocacy group called the Alleged Lunatics’ Friend Society. His writings express a forgotten perspective in the history of psychiatry: the response of alleged lunatics themselves to the narrowing epistemology of modern psychological medicine.