Abu Ḥamid al-Ghazali (1058-1111), theologian, logician, jurist and mystic, was born and died in Ṭus in Central Asia, but spent much of his life lecturing at Baghdad or leading the life of a wondering dervish. His most celebrated work, of which this is an important chapter, has exercised a profound influence on Muslim intellectual history by exploring the mystical significance of the practices and beliefs of Islamic orthodoxy, earning him the title of Ḥujjat al Islam, the 'Proof of Islam'.