In 1095 the most prestigious academic in the Islamic world walked into his Baghdad lecture hall, opened his mouth, and could not speak. Within days he could not eat, and the empire’s best doctors concluded his illness was spiritual. This episode traces the life of Al-Ghazali, born around 1058 in Tus, Persia, who studied under Al-Juwaini in Nishapur, caught the eye of the Seljuk vizier Nizam al-Mulk, and was appointed head of the Nizamiyya in Baghdad in his early thirties, tasked with dismantling Ismaili arguments and defending Sunni orthodoxy. We explore why the higher he climbed, the more hollow he felt, until he recognized his motives as ego and prestige rather than truth.

We follow his fabricated Hajj cover story, his liquidation of his wealth, and his decade of seclusion sweeping floors at the Umayyad Mosque in Damascus, moving between Jerusalem and Mecca. From that isolation came Deliverance from Error, his account of an epistemological crisis, The Revival of the Religious Sciences, which reconciled legalistic orthodoxy with Sufi mysticism, and The Incoherence of the Philosophers, with its cotton and fire argument for occasionalism. We examine the fierce debate over whether he killed Islamic science, his call for tolerance in The Decisive Criterion, his balanced economic ethics, his return to teaching in 1106, his death in 1111, and his influence on Rumi, Maimonides, Aquinas, Descartes, and Hume.

• Why heading the Nizamiyya was like being chief justice and pope at once
• The difference between knowing the definition of drunkenness and being drunk
• How the shell of outward practice protects the pearl of inner mysticism
• The competing views of scholars Nuh Aydin, George Saliba, and Hassan Hassan on science after Al-Ghazali
• Why he warned that denying the mathematics of an eclipse is a crime against religion