Not until the beginning of the tenth century A.D. did the orthodox Mohammedan dogma begin to emerge from the clash of opinions into its definite shape. The Mu'tazilites had advocated man's free will; had given prominence to justice and holiness in their conception of God, had denied distinct qualities in God and the eternity of God's Word; had accepted a place for the neutral between Paradise and Hell; and for some time the favour of the powers in authority seemed to assure the victory of their system. Al-Ash'arî contradicted all these points, and his system has in the end been adopted by the great majority. The Mu'tazilite doctrines for a long time still enthralled many minds, but they ended by taking refuge in the political heresy of Shî'itism. In the most conservative circles, opponents to all speculation were never wanting; but they were obliged unconsciously to make large concessions to systematic thought; for in the Moslim world as elsewhere religious belief without dogma had become as impossible as breathing is without air. Thus, in Islâm, a whole system, which could not even pretend to draw its authority from the Sunnah, had come to be accepted. It was not difficult to justify this deviation from the orthodox abhorrence against novelties. Islâm has always looked at the world in a pessimistic way, a view expressed in numberless prophetic sayings. The world is bad and will become worse and worse. Religion and morality will have to wage an ever more hopeless war against unbelief, against heresy and ungodly ways of living. While this is surely no reason for entering into any compromise with doctrines which depart but a hair's breadth from Qorân and Sunnah, it necessitates methods of defence against heresy as unknown in Mohammed's time as heresy itself. "Necessity knows no law" is a principle fully accepted in Islam; and heresy is an enemy of the faith that can only be defeated with dialectic weapons. So the religious truths preached by Mohammed have not been altered in any way; but under the stress of necessity they have been clad in modern armour, which has somewhat changed their aspect. Moreover, Islâm has a theory, which alone is sufficient to justify the whole later development of doctrine as well as of law. This theory, whose importance for the system can hardly be overestimated, and which, nevertheless, has until very recent times constantly been overlooked by Western students of Islâm, finds its classical expression in the following words, put into the mouth of Mohammed: "My community will never agree in an error." In terms more familiar to us, this means that the Mohammedan Church taken as a whole is infallible; that all the decisions on matters practical or theoretical, on which it is agreed, are binding upon its members. Nowhere else is the catholic instinct of Islâm more clearly expressed.