"...more extraordinary the more it is studied, because what it states about a subject which is by definition beyond verbalization." -- Doris Lessing, Encounter: Books & Writers, August 1972

"...the best introduction to the body of Shah's work...one is ... forced to use one's mind in a new way." -- Doris Lessing, New York Times Book Review, May 7, 1971

"...vastness of learning and exposition that calls to our patience - and perhaps to our loss if it calls in vain." -- Stevie Smith, The Observer, November 1, 1964

"Important historically and culturally." -- Los Angeles Times

"The book has flashes of what (without intending to define the word) I can only call illumination." -- D. J. Enright, New Statesman

"The first fully authoritative book on Sufism and the human-development system of the 'dervishes'..." -- Afghanistan News, May 1964