Early Sufi master Abū Bakr al-Shiblī (d. 946) is both famous and unknown. One of the pioneers of Islamic mysticism, he left no writings, but his legacy was passed down orally, and he has been acclaimed from his own time to the present. Accounts of Shiblī present a fascinating figure: an eccentric with a showy red beard, a lover of poetry and wit, an ascetic who embraced altered states of consciousness, and, for a time, a disturbed man confined to an insane asylum. Kenneth Avery offers a contemporary interpretation of Shiblī's thought and his importance in the history of Sufism. This book surveys the major sources for Shiblī's life and work from both Arabic and Persian traditions, detailing the main facets of his biography and teachings and documenting the evolving figure of a Sufi saint. Shiblī's relationships with his more famous colleague Junayd and his infamous colleague Ḥallāj are discussed, along with his Qur'ānic spirituality, his poetry, and the question of his periodic insanity.