Abstract
William Butler (1535-1618) was a man without a medical degree who was styled as the 'greatest physician of his age'. He was famous in his lifetime, and in the latter stages of his career was involved with the royal court, attending to King James I and his son, Prince Henry. Butler was an empiricist who practiced confidently and compassionately in a time of limited medical understanding. He was also a man of contradictions: he was loved and respected by his contemporaries but could be cantankerous and obtuse; he was anti-establishment, complaining bitterly about the restrictive monopolisation of medicine sustained by the Royal College of Physicians, but advanced his career via connections within the aristocracy; he sometimes practiced orthodox Galenic medicine, but was at times highly unconventional in his treatments. Posthumously, despite some compelling historical studies of Butler, there has been a great deal of embellishment of his behaviour and practice. This biography draws from Butler's own letters, contemporary writers and modern scholarly literature. It aims to arrange these sources into a verifiable narrative of this singular physician's life.