The Mouride tariqa (brotherhood) is headquartered in Ṭūbā, in north-central Senegal, the site of Amadu Bamba Mbaké's 1890s vision of the angel Gabriel and the location for the brotherhood’s Grand Magal, an annual pilgrimage that attracts as many as two million devotees. The brotherhood grew out of the Qādiriyya (Xaadir) tariqa, a Ṣūfī movement to which Bamba was himself an adherent. Three distinctive features mark the Mourides. First, their devotion to their order's founder, Amadu Bamba, mirrors the level of veneration often reserved by Muslims for the Prophet Muhammad. Second, their adherence to the principle of hard works makes them ideally suited for agrarian life in the Senegalese countryside. Third, their commitment to principled Islam...