Al-Ghazali (1058-1111 A. D.) has generally been known as one of the greatest innovators of the orthodox Islamic thought. It has often been claimed, however, that he had the unpublicized “esoteric” teachings. That is to say, he was in reality a philosopher (failasuf) in the disguise of an orthodox Sufi doctor, in spite of the fact that he once officially denounced philosophers as the dire enemy of the Sunni Islam. Ibn Rushd, a famous Muslim philosopher, was the first to propagate the allegation. In fact, there are some “evidences” favorable for the indictment. First, al-Ghazali hints here and there in his writings that he has some secret ideas which he cannot disclose except to the initiate. Second, there are some works attributed to al-Ghazali which are apparently Neoplatonic in nature. Many scholars, Muslim and non-Muslim, have devoted many articles and books to the study of this problem of the alleged “esoteric” teachings ever since the end of the 19 th century. Particularly the third part of al-Ghazali's Mishkat al-Anwar has attracted the attention of the scholars because of its mystical thought of Neoplatonic tendency.