Maulana Jalal al-Din Rumi 
Revival: Rumi, Poet and Mystic, 1207-1273 (1950) [PDF ebook] 
Selections from his Writings, Translated from the Persian with Introduction and Notes

To the English reader the mysticism of Rumi opens a new world of spiritual and poetical experience. ‘God is One but religions are many’ runs the Sufi teaching; and the English reader can here enlarge his experience by apprehending the mystic intuition of a great Persian poet. The late author”s beautiful and faithful translations are illuminated by Notes on Sufi doctrine and experience. The author did not finish the Introduction, but it has been completed by his old pupil and friend, Professor A. J. Arberry, who has seen the book through the press.