The fifty years which run from 628 to 678 contain the various acts of one prolonged attempt by the Byzantine emperors to enforce their religious despotism on the Pope in the shape of the Monothelite heresy. The two standard-bearers of the heresy are two patriarchs, Sergius at Constantinople, and Cyrus at Alexandria. Precisely at this time the Mohammedan power appears upon the scene. While Heraclius is brooding over the compromise of Sergius for reuniting an empire dislocated by heresy, Mohammed is purposing the foundation of an empire resting on material force. While Heraclius is assuming the right to define the doctrine of the Church in virtue of his imperial power, Mohammed is constructing a claim to prophetic rank from which imperial power itself shall emanate. The Mohammedan claim is the exact antithesis of the Byzantine usurpation: the rise of a false prophet punishes the attempt among Christians to rule the spiritual by the civil power. Upon the death of Mohammed in 632, his companions took counsel together and elected Abu Bekr to carry on the dominion based upon religion which Mohammed had invented. They gave him the title of “Chalif of God’s Apostle”. As the vicar of the new prophet, he was to exert the absolute power which belonged to the prophet’s office, and of which the civil sovereignty was an offshoot. This power was rooted in the belief that Mohammed had been sent by God. The quality therefore of every act exercised by the first chalif, and by every successor, depended on the truth of such a mission. By the choice of Abu Bekr, father of Aischa, the favourite wife of Mohammed, it was resolved that the succession to the chalifate should be elective, not hereditary. The most stirring principle of the new power was that everyone who died for its extension, which was called the Holy War, should pass at once to paradise. Paradise had been drawn by Mohammed after his own sensual imagination to suit the taste of a most sensual people. The empire sought by Mohammed and his followers was to be imposed by force. Abu Bekr stirred up the sons of the desert to this Holy War, proclaiming that he who fought for God’s cause should have 700 good works counted for each step, 700 honours allotted to him, and 700 sins forgiven. Abu Bekr held the chalifate but two years, dying in 634 at the age of 63 years. But at the very time of his death the pearl of Syria, Damascus, fell into the hands of his generals, Amrou and Khaled. From Medina the city of the prophet, and the seat of the chalif, he had sent forth three armies. Moseilama, a prophet who competed with Mohammed, was destroyed, the discontented tribes in Arabia itself were reduced to obedience. The Persian provinces on the Euphrates were attacked. The Roman empire itself was summoned to accept the new religion, or to become tributary.