Originally written as a manual of spiritual instruction, this crucial work of medieval Islamic thought examines Sufi and mystical influences within the Muslim tradition to provide insight into the intellectual and religious history of the Muslim world. Written by one of the most famous theologian-mystics of all time, it is an in-depth discussion of two essential virtues of the religious and spiritual life: patience and thankfulness. Compelling and insightful, this exploration defines these virtues and examines their place in the Islamic worldview, with particular attention paid to their attainment and the influences that divert people from these virtues. This first-ever academic translation includes an introduction to the structure and development of al-Ghazali's thought, as well as a biography, appendix, and index.