The relation of individual Sūfīs to Islam varies from more or less entire conformity to a merely nominal profession of belief in Allah and His Prophet. While the Koran and the Traditions are generally acknowledged to be the unalterable standard of religious truth, this acknowledgment does not include the recognition of any external authority which shall decide what is orthodox and what is heretical. Creeds and catechisms count for nothing in the Sūfī’s estimation. Why should he concern himself with these when he possesses a doctrine derived immediately from God? As he reads the Koran with studious meditation and rapt attention, lo, the hidden meanings--infinite, inexhaustible--of the Holy Word flash upon his inward eye. This is what the Sūfīs call _istinbāt_, a sort of intuitive deduction; the mysterious inflow of divinely revealed knowledge into hearts made pure by repentance and filled with the thought of God, and the outflow of that knowledge upon the interpreting tongue. Naturally, the doctrines elicited by means of _istinbāt_ do not agree very well either with Mohammedan theology or with each other, but the discord is easily explained. Theologians, who interpret the letter, cannot be expected to reach the same conclusions as mystics, who interpret the spirit; and if both classes differ amongst themselves, that is a merciful dispensation of divine wisdom, since theological controversy serves to extinguish religious error, while the variety of mystical truth corresponds to the manifold degrees and modes of mystical experience. In the chapter on the gnosis I shall enter more fully into the attitude of the Sūfīs towards positive religion. It is only a rough-and-ready account of the matter to say that many of them have been good Moslems, many scarcely Moslems at all, and a third party, perhaps the largest, Moslems after a fashion. During the early Middle Ages Islam was a growing organism, and gradually became transformed under the influence of diverse movements, of which Sūfism itself was one. Mohammedan orthodoxy in its present shape owes much to Ghazālī, and Ghazālī was a Sūfī. Through his work and example the Sūfistic interpretation of Islam has in no small measure been harmonised with the rival claims of reason and tradition, but just because of this he is less valuable than mystics of a purer type to the student who wishes to know what Sūfism essentially is.