Koran, and even as being able to supersede its ordinances, while he also recognized the universal custom (_ijma`_) of the Moslem world as divine and binding. His four bases of religion--Koran, sunna, qiyas and ijma`--have been generally accepted in Islam (see above). Ibn Hanbal's position has been already mentioned. All these four schools are reckoned orthodox, and all orthodox Moslems belong to one or another of them. Another teacher of this time, who founded a school which did not succeed in being recognized as orthodox, was Da`ud uz-Zahiri. Trained as a Shafi`ite, he became too strict for this school, rejected analogy, restricted _ijma`_ to the agreement or custom of the companions of Mahomet, and accepted the whole of the Koran and tradition in the most literal and external sense. His followers were called Zahirites (i.e. externalists). After Ash`ari's time these principles were applied to theology by Ibn Hazm (q.v.) see I. Goldziher, _Die Zahiriten, ihr Lehrsystem und ihre Geschichte_ (Leipzig, 1884). Before turning to the reform of Ash`ari and the introduction into orthodox theology of scholastic philosophy it is necessary to notice another phase of religious life which became the common property of orthodox and heretics. This was the introduction of asceticism in religions practice and of mysticism in religious thought. Sufi`ism (q.v.), which combined these two, is rightly not counted among the sects of Islam. Asceticism seems to have won a certain amount of approval from Mahomet himself, who much respected the Christian monks. The attention paid in early Islam to the joys and punishments of the future life led to self-denial and simple living in this world. An Arabian writer, speaking of the simplicity of manners of the first four caliphs, says that their affairs were conducted with more consideration of the future life than of this world. Many Moslems went even farther than these caliphs, and gave up all concern as far as possible with the affairs of this world and lived in poverty, in wanderings or in retirement (see DERVISH). For the historical development of this movement, with its accompanying mysticism, see SUFI`ISM. Ash`ari (d. before 942) was for forty years a Mu`tazilite, then became orthodox (see ASH`ARI), and at once applied rational methods for the support and interpretation of the orthodox faith. Before him, reason had not been allowed any scope in orthodox theology. He was not the first to use it; some teachers (as al-Junaid) had employed it in teaching, but only in secret and for the few. The methods of scholastic philosophy were now introduced into Moslem theology. The chief characteristic of his religious teaching was the adoption of the _via media_ between materialistic grossness and the ideas of pure speculative philosophy. Thus he taught, as to the attributes of God, that they exist, but are not to be compared with human attributes; as to His visibility, that He can be seen but without the limitations of human sight.