The Arabian empire was now of immense extent. Egypt, Syria, and Persia had been conquered in the reign of Omar. Under the first khalifs of the dynasty of the Ommiades (so called from Ommiyah, the great-grandfather of Moawiya), the conquest of Africa and Spain was achieved, and the later princes of this family ruled over the most extensive empire of the world. The great schism of the Mohammedan church (we must be permitted to employ this term, the only one our language affords) commences with the accession of the house of Ommiyah. The Mohammedans have, as is generally known, been from that time to the present day divided into two great sects, the Soonees and the Sheähs, the orthodox and the dissenters, as we might venture to call them, whose opposite doctrines, like those of the Catholics and the Protestants of the Christian church, are each the established faith of great and independent nations. The Ottoman and the Usbeg Turks hold the Soonee faith; the Persians are violent Sheähs; and national and religious animosity concur in making them the determined and inveterate foes of each other. The Soonees hold that the first four khalifs were all legitimate successors of the Prophet; but as their order was determined by their degree of sanctity, they assign the lowest rank to Ali. The Sheähs, on the contrary, maintain that the dignity of the Prophet rightfully descended to the son of his uncle and the husband of his daughter. They therefore regard Aboo Bekr, Omar, and Othman, as usurpers, and curse and revile their memory, more especially that of the rigid Omar, whose murderer they venerate as a saint. It must be steadily kept in mind, in every discussion respecting the Mohammedan religion, that Mohammed and his successors succeeded in establishing what the lofty and capacious mind of Gregory VII. attempted in vain--the union of the civil and ecclesiastical powers in the same person. Unlike the schisms of the eastern and western, of the Catholic and Protestant churches, which originated in difference of opinion on points of discipline or matters of doctrine, that of the Mohammedans arose solely from ambition and the struggle for temporal power. The sceptre of the greatest empire of the world was to be the reward of the party who could gain the greatest number of believers in his right to grasp the staff and ascend the pulpit of the Prophet of God. Afterwards, when the learning of the Greeks and the Persians became familiar to the Arabs, theological and metaphysical niceties and distinctions were introduced, and the two great stems of religion threw out numerous sectarian branches. The Soonees are divided into four main sects, all of which are, however, regarded as orthodox, for they agree in the main points, though they differ in subordinate ones. The division of the Sheähs is also into four sects, the point of agreement being the assertion of the right of Ali and his descendants to the imamat, or supreme ecclesiastical dignity;