Omar Khayyam 
The Sufistic Quatrains [EPUB ebook] 

‘We may look upon Omar as a deeply learned man, following his own convictions, who, tortured with the question of existence, and finding no solution to life in Musulman dogmas, worked out for himself a regular conception of life based on Sufistic Mysticism; a man who, without discarding belief, smiled ironically at the inconsistencies and peculiarities of the Islam of his time, which left many minds dissatisfied in the fourth and fifth centuries, needing as it did vivification. It found this in the person of Ghazzali, who in this movement assigned the proper place to the Mystic element. Omar was a preacher of moral purity and of a contemplative life; one who loved his God and struggled to master the eternal, the good, and the beautiful.’