After his overwhelming and life-altering encounters with Shams of Tabriz, Rumi, the great thirteenth-century mystic, poet, and originator of the whirling dervishes, let go of many of the precepts of formal religion, insisting that only a complete personal dissolving into the larger energies of God could provide the satisfaction that the heart so desperately seeks. He began to speak spontaneously in the language of poetry, and his followers compiled...