Imam al-Ghazali's Ihya' Ulum al-Din

1111) wrote "Ihyā'u Ulūmi'd-Dīn" (The Revival of the Religious Sciences). After teaching at the Nizamiyya madrasa he passed through a period of personal crisis and then composed this transformative work, which achieved a synthesis of Sunni Islam and Sufism. It was the most brilliant fruit of the intellectual environment that flourished under Seljuk patronage.