While Mahomet was still an exile at Medinah it is evident that he already contemplated the idea of gaining the world for Islam. ‘Let there be in you a nation summoning unto good,’ says the Koran, and in token of this mission the Prophet, in the years following his Arabian victories, sent letters to foreign rulers to announce his ambition. Here is one to the chief of the Copts, a Christian race living in Egypt: ‘In the name of Allah ... the Merciful. ‘From the Apostle of Allah to ..., Chief of the Copts. Peace be upon him who follows the guidance. Next I summon thee with the appeal to Islam: become a Moslem and thou shalt be safe. God shall give thee thy reward twofold. But if thou decline then on thee is the guilt of the Copts. O ye people of the Book come unto an equal arrangement between us and you that we should serve none save God, associating nothing with Him, and not taking one another for Lords besides God,--and if ye decline, then bear witness that we are Moslems.’ [Sidenote: The Kingdom of Persia] Similar letters were sent to Chosroes, King of Persia, and to Heraclius, the Christian Emperor at Constantinople. The former tore the letter in pieces contemptuously, for at that time his kingdom extended over the greater part of Asia; Jerusalem, once the pride of the Eastern Empire, had fallen into his grasp; while his armies were besieging Constantinople itself. A letter that he himself penned to the Christian Emperor shows his overweening pride, and the depths into which Byzantium had fallen in the public regard: ‘Chosroes, Greatest of Gods, and Master of the whole earth, to Heraclius, his vile and insensate slave. Why do you still refuse to submit to our rule and call yourself a king? Have I not destroyed the Greeks? You say that you trust in your God. Why has he not delivered out of my hand Caesarea, Jerusalem, Alexandria? and shall I not also destroy Constantinople? But I will pardon your faults if you will submit to me, and come hither with your wife and children, and I will give you lands, vineyards, and olive groves, and look upon you with a kindly aspect. Do not deceive yourself with vain hope in that Christ, who was not even able to save himself from the Jews, who killed him by nailing him to a cross. Even if you take refuge in the depths of the sea I shall stretch out my hand and take you, so that you shall see me whether you will or no.’