[1086] A violent orthodox reaction set in under the worthless and Turk-ruled Khalif Motawakkel [1087] (847-861), by whose time the Khalifate was in a state of political decadence, partly from the economic exhaustion following on its tyrannous and extortionate rule; partly from the divisive tendencies of its heterogeneous sections; partly from the corrupting tendency of all despotic power. [1088] Despite the official restoration of orthodoxy, the private cultivation of science and philosophy proceeded for a time; the study and translation of Greek books continued; [1089] and rationalism of a kind seems to have subsisted more or less secretly to the end. In the tenth century it is said to have reached even the unlearned; and though the Motazilites gradually drifted into a scholastic orthodoxy, downright unbelief came up alongside, [1090] albeit secretly. Faith in Mohammed's mission and law began again to shake; and the learned disregarded its prescriptions. Mystics professed to find the way to God without the Koran. Many decided that religion was useful for regulating the people, but was not for the wise. On the other side, however, the orthodox condemned all science as leading to unbelief, [1091] and developed an elaborate and quasi-systematic theology. It was while the scientific encyclopedists of Bassorah were amassing the knowledge which, through the Moors, renewed thought in the West, that Al Ashari built up the Kalâm or scholastic theology which thenceforth reigned in the Mohammedan East; [1092] and the philosopher Al Gazzali (or Gazel), on his part, employed the ancient and modern device of turning a profession of philosophical scepticism to the account of orthodoxy. [1093] In the struggle between science and religion, in a politically decadent State, the latter inevitably secured the administrative power. [1094] Under the Khalifs Motamid (d. 892) and Motadhed (d. 902) all science and philosophy were proscribed, and booksellers were put upon their oath not to sell any but orthodox books. [1095] Thus, though philosophy and science had secretly survived, when the political end came the popular faith was in much the same state as it had been under Haroun Al Raschid. Under Islam as under all the faiths of the world, in the east as in the west, the mass of the people remained ignorant as well as poor; and the learning and skill of the scholars served only to pass on the saved treasure of Greek thought and science to the new civilization of Europe. The fact that the age of military and political decadence was that of the widest diffusion of rationalism is naturally fastened on as giving the explanation of the decline; but the inference is pure fallacy. The Bagdad Khalifate declined as the Christianized Roman Empire declined, from political and external causes; and the Turks who overthrew it proceeded to overthrow Christian Byzantium, where rationalism never reared its head.