Ihya Ulum al-Din

The Ihya Ulum al-Din, the Revival of the Religious Sciences, is Abu Hamid al-Ghazali's vast systematic treatise on Islamic spiritual and ethical life, organized into four quarters covering the outward acts of worship, the norms of everyday social conduct, the vices that destroy the soul, and the virtues that save it, moving a reader step by step from external observance toward inner transformation.

Al-Ghazali composed it after abandoning his prestigious teaching post at the Nizamiyya college in Baghdad around 1095, following what he described as a personal crisis of certainty that led him first into skepticism and then into a period of withdrawal and Sufi practice, an experience the Ihya draws on directly even as it remains a work of systematic instruction rather than autobiography. The book deliberately builds a bridge between the outward legal and theological sciences that dominated mainstream Sunni scholarship and the inward disciplines of Sufism, which many jurists of al-Ghazali's time regarded with suspicion, arguing at length that the two are not in competition but that correct outward practice is empty without the inward states the Sufis cultivated. Each of the four quarters is itself further subdivided into ten books, giving the whole work a scale closer to an encyclopaedia than to a single treatise.

The Ihya's lasting historical importance lies substantially in this reconciling function: after its wide circulation, mainstream Sunni orthodoxy increasingly treated moderate Sufi practice as a legitimate, even necessary, complement to legal and theological learning rather than as a suspect deviation from it, a shift historians of Islam credit al-Ghazali's work with doing more than any other single book to accomplish. It remains, alongside the Quran and the major hadith collections, among the most widely read and cited works in the entire history of Islamic religious literature, still assigned in traditional centers of learning and still printed in countless editions and abridgments across the Muslim world.

The book's influence extended well beyond specifically Sufi circles, shaping mainstream Sunni devotional and ethical writing broadly, and its detailed treatment of specific vices and virtues, pride, envy, patience, gratitude and many others, gave later writers a durable framework for ethical instruction independent of its more explicitly mystical passages. Al-Ghazali himself regarded the Ihya as the summation of his mature thought, superseding much of his earlier, more purely philosophical and legal writing.