The Mohammedan world is roughly divided into Sunnis and Shia. The Shia are the idealists, the mystics of Islam; the Sunnis are the formalists, the schoolmen. The Shia trace an apostolic succession from Ali, the husband of the prophet Mohammed's daughter Fatima, hold doctrines of immanence and illumination, adopt an allegorical interpretation of scripture, and believe in the coming of a Mahdi or Messiah. The Sunnis adhere to the elective historical caliphate descended from Mohammed's uncle, maintain the eternal uncreated sufficiency of the Koran, literally interpreted, and believe in no Messiah save Mohammed. The Shia, whatever their racial origin, form the Persian, the Aryan, adaptation of Islam, which is an essentially Semitic creed. In the tenth century they had established a caliph among the Berbers at Kayrawan (908). They had thence invaded Egypt with temporary success in 914 and 919. When the death of Kafur in 968 left the country a prey to rival military factions, the fourth of the caliphs of Kayrawan--called the Fatimid caliphs, because they claimed a very doubtful descent from Fatima--sent his army into Egypt. The people, who had too long been the sport of Turkish mercenaries, received the invaders as deliverers, just as the Copts had welcomed the Arabs three centuries before. Gauhar, the Fatimid general, entered Fustat (or Misr, as it was usually called, a name still applied both to Egypt and to its capital) amid acclamations in 969, and immediately laid the foundations of the fortified palace which he named, astrologically, after the planet Mars (Kahir), El-Kahira, "the Martial," or "the Victorious," which gradually expanded to the city of Cairo. He also founded the great historic university mosque of the Azhar, which, begun by the heretical Shia, became the bulwark of rigid scholasticism and the theological centre of orthodox Islam. The theological change was abrupt. It was as though Presbyterian Scotland had suddenly been put under the rule of the Jesuits. But, like the Society of Jesus, the Shia were pre-eminently intellectual and recognised the necessity of adapting their teaching to the capacities of their hearers, and the conditions of the time. They did not force extreme Shia doctrine upon the Egyptians. Their esoteric system, with its graduated stages of initiation, permitted a large latitude, and they were content to add their distinctive formulas to the ordinary Mohammedan ritual, and to set them conspicuously on their coinage, without entering upon a propaganda. The bulk of the Egyptian Moslems apparently preserved their orthodoxy and suffered an heretical caliphate for two centuries with traditional composure. The Christian Copts found the new _régime_ a marked improvement. Mysticism finds kindred elements in many faiths, and the Fatimid caliphs soon struck up relations with the local heads of the Christian religion.