He came next to examine the doctrine of the Ta‘limites. They, a somewhat outlying wing of the Fatimid propaganda, had come at this time into alarming prominence. In 483 Hasan ibn as-Sabbah had seized Alamut and entered on open rebellion. The sect of the Assassins was applying its principles. But the poison of their teaching was also spreading among the people. The principle of authority in religion, that only by an infallible teacher could truth be reached and that such an infallible teacher existed if he could only be found, was in the air. For himself, al-Ghazzali found the Ta‘limites and their teaching eminently unsatisfactory: They had a lesson which they went over parrot-fashion, but beyond it they were in dense ignorance. The trained theologian and scholar had no patience with their slackness and shallowness of thought. He labored long, as ash-Shahrastani later confesses that he, too, did, to penetrate their mystery and learn something from them; but beyond the accustomed formulæ there was nothing to be found. He even admitted their contention of the necessity of a living, infallible teacher, to see what would follow—but nothing followed. “You admit the necessity of an Imam,” they would say. “It is your business now to seek him; we have nothing to do with it.” But though neither al-Ghazzali nor ash-Shahrastani, who died 43 (lunar) years after him, could be satisfied with the Ta‘limites, many others were. The conflict was hot, and al-Ghazzali himself wrote several books against them. [Sidenote: STUDY OF SUFIISM] The other possibility, the path of the mystic, now lay straight before him. In the _Munqidh_ he tells us how, when he had made an end of the Ta‘limites, he began to study the books of the Sufis, without any suggestion that he had had a previous acquaintance with them and their practices. But probably this means nothing more than it does when he speaks in a similar way of studying the scholastic theologians; namely, that he now took up the study in earnest and with a new and definite purpose. He therefore read carefully the works of al-Harith al-Muhasibi, the fragments of al-Junayd, ash-Shibli, and Abu Yazid al-Bistami. He had also the benefit of oral teaching; but it became plain to him that only through ecstasy and the complete transformation of the moral being could he really understand Sufiism. He saw that it consisted in feelings more than in knowledge, that he must be initiated as a Sufi himself; live their life and practise their exercises, to attain his goal.