"Islam is a religion adapted to Orientals, especially Arabs, i.e., on one hand to townsmen engaged in trade and industry, on the other to nomadic Bedouins. Therein lies, however, the embryo of a periodically recurring collision. The townspeople grow rich, luxurious and lax in the observation of the "law." The Bedouins, poor and hence of strict morals, contemplate with envy and covetousness these riches and pleasures. Then they unite under a prophet, a Mahdi, to chastise the apostates and restore the observation of the ritual and the true faith and to appropriate in recompense the treasures of the renegades. In a hundred years they are naturally in the same position as the renegades were: a new purge of the faith is required, a new Mahdi arises and the game starts again from the beginning. That is what happened from the conquest campaigns of the African Almoravids and Almohads in Spain to the last Mahdi of Khartoum who so successfully thwarted the English. It happened in the same way or similarly with the risings in Persia and other Mohammedan countries. All these movements are clothed in religion but they have their source in economic causes; and yet, even when they are victorious, they allow the old economic conditions to persist untouched. So the old situation remains unchanged and the collision recurs periodically. In the popular risings of the Christian West, on the contrary, the religious disguise is only a flag and a mask for attacks on an economic order which is becoming antiquated. This is finally overthrown, a new one arises and the world progresses."