146 THE LIFE OF SCIENCE 



About the year a.d. 610, a new prophet appeared at Mecca, in 

 Hejaz, Abu-1-Qasim Muhammad of the tribe of Quraysh, who 

 was like a new incarnation of the old Hebrew prophets. At first the 

 people did not pay much attention to him, but after he had 

 abandoned his native town and moved two hundred and fifty-five 

 miles northward to al-Medina, in 622, his success was phe- 

 nomenal. No prophet was ever more successful. By the time of his 

 death ten years later, he had managed to unite the Arabian tribes 

 and to inspire them with a single-hearted fervor which would 

 enable them later to conquer the world. Damascus was captured 

 in 635, Jerusalem in 637; the conquest of Egypt was completed 

 in 641, that of Persia in the following year, that of Spain some- 

 what later in 710/12. By this time the Muslims, that is the 

 Prophet's followers, were ruling a large belt of the world all the 

 way from Central Asia to the Far West. The conquest of Persia 

 was especially momentous because it brought the invaders, brave 

 but uncouth, into touch with an old and very refined civilization, 

 that of Iran. I did not speak of it before because it is difficult to 

 state its earlier contributions with sufficient brevity, and more 

 difficult, if not impossible, to date them. For the purpose of a 

 sketch like this, it is sufficient to introduce Iran at this juncture, 

 but its part henceforth was considerable. The new dynasty of 

 Muslim caliphs, the f Abbasid (750-1258) established its capital 

 in Baghdad on the Tigris, and for a time that new city was one 

 of the main centers of the civilized world. The 'Abbasids were 

 from the beginning under the Iranian spell. Their religious and 

 moral strength was derived from their ancestral home, Arabia; 

 their urbanity, their humanism, from Persia. To put it in a nut- 

 shell, the new Muslim civilization was essentially due to the graft- 

 ing of the vigorous Arabic scion upon the old Iranian tree. This 

 explains at once its astounding robustness and its changing 

 qualities. 



Under the impulse of these two tremendous forces, Muslim 

 fanaticism and Persian curiosity, and under the guidance of a 

 series of 'Abbasid caliphs who had a passion for knowledge — 



