Abu Hamid Muhammad ibn Muhammad al-Ghazali (AH 450?505 / 1058?1111 CE) was born in Tus, in the Khorasan region of present-day Iran. He received his early education there before traveling to study under the eminent Ash'ari theologian Imam al-Haramayn al-Juwayni at the Nizamiyyah madrasa in Nishapur. By the age of thirty-three he had been appointed to lead the prestigious Nizamiyyah madrasa in Baghdad ? at that time the intellectual center of the Sunni Islamic world ? a position that brought him into close contact with the Seljuk court and the leading scholars of his generation.

At the height of his influence, al-Ghazali underwent a profound spiritual crisis that he describes with unflinching introspection in his autobiographical work Deliverance from Error (al-Munqidh min al-Dalal). Dissatisfied with what he perceived as the inadequacy of both scholastic theology (kalam) and Aristotelian-Neoplatonic philosophy to address the deepest questions of certainty and the soul's journey to God, he resigned his position in 1095 CE and embarked on a decade of withdrawal, travel, and contemplative practice ? in Damascus, Jerusalem, Mecca, and Medina ? before returning to teaching in his later years.

The intellectual legacy of al-Ghazali spans jurisprudence (fiqh) in the Shafi'i school, Ash'ari theology, the critique of Islamic philosophy (most famously in his Tahafut al-Falasifa ? The Incoherence of the Philosophers), and the synthesis of Sufi ethics and practice with mainstream Sunni theology. His magnum opus, Ihya' 'Ulum al-Din (Revival of the Religious Sciences), remains one of the most widely read and influential works in the Islamic scholarly tradition.

Al-Ghazali is universally regarded as one of the foremost authorities in Islamic intellectual history. His title, Hujjat al-Islam ? the Proof of Islam ? reflects the esteem in which subsequent generations held his contribution to stabilizing and deepening Sunni theological and spiritual life. His works continue to be studied in traditional Islamic seminaries (madaris) and modern academic institutions across the world.