While the progressive period lasted, there was of course an abundance of practical freethought. But after a marvellously rapid rise, the Moorish civilization was arrested and paralysed by the internal and the external forces of anti-civilization--religious fanaticism within and Christian hostility without. Everywhere we have seen culture-progress depending more or less clearly on the failure to find solutions for political problems. The most fatal defect of all Arab civilization--a defect involved in its first departure by way of conquest, and in its fixedly hostile relation to the Christian States, which kept it constantly on a military basis--was the total failure to substitute any measure of constitutional rule for despotism. It was thus politically unprogressive, even while advancing in other respects. But in other respects also it soon reached the limits set by the conditions. Whereas in Persia the Arabs overran an ancient civilization, containing many elements of rationalism which acted upon their own creed, the Moors in Spain found a population only slightly civilized, and predisposed by its recent culture, as well as by its natural conditions, [1148] to fanatical piety. Thus when, under their tolerant rule, Jews and Christians in large numbers embraced Islam, the new converts became the most fanatical of all. [1149] All rationalism existed in their despite, and, abounding as they did, they tended to gain power whenever the Khalif was weak, and to rebel furiously when he was hostile. When, accordingly, the growing pressure of the feudal Christian power in Northern Spain at length became a menacing danger to the Moorish States, weakened by endless intestine strife, the one resource was to call in a new force of Moslem fanaticism in the shape of the Almoravide [1150] Berbers, who, to the utmost of their power, put down everything scientific and rationalistic, and established a rigid Koranolatry. After a time they in turn, growing degenerate while remaining orthodox, were overrun by a new influx of conquering fanatics from Africa, the Almohades, who, failing to add political science to their faith, went down in the thirteenth century before the Christians in Spain, in a great battle in which their prince sat in their sight with the Koran in his hand. [1151] Here there could be no pretence that "unbelief" wrought the downfall. The Jonah of freethought, so to speak, had been thrown overboard; and the ship went down with the flag of faith flying at every masthead. [1152]