The idea that ethics might be fruitfully understood in analogy with, or indeed as a form of, medicine has enjoyed a long and distinguished history. A staple of ancient philosophical thinking, it also achieved wide expression in the Islamic world. This essay explores the role of the medical analogy in the work of the eleventh-century Muslim intellectual Abū Hāmid al-Ghazālī. Al-Ghazālī’s use of this analogy offers a unique vantage point for approaching several key features of his ethics of virtue, as notably expressed in the Revival of the Religious Sciences. These include his understanding of the nature of virtue and moral education; the fundamental structure of value; and most importantly, the place of human reasoning in the ethical life. This analogy also illuminates the rhetorical context of the Revival, taken as a book that aims to foster skills of practical reasoning and train its readers to become their own physicians.