PROGRESS AMONG THE ARABS. 39 



six centuries. He described small-pox, unknown to the 

 Greeks ; was the first to use coloured drawings to instruct 

 students. He is the author of an Encyclopaedia which 

 shows the vastness of his acquirements. He explained the 

 GEOLOGICAL FORMATION of mountain-ranges in a very lucid 

 manner; he likewise guessed the correct origin of fossils 

 a double feat which implies practical and personal observa- 

 tion of nature, thus anticipating the theories of uprisings, 

 alluvion, and erosion. " FOSSILS/' he says, "prove that the 

 rocks were deposited by water." He explained the nature 

 of petrifying waters ; mentioned meteorites, and made several 

 discoveries about minerals. He also contributed to the 

 knowledge of the plants of Bactria and Sogdiana, so fertile 

 in medical plants. He is, besides, the first philosopher who 

 started FREE INQUIRY, and thus inaugurated the age of 

 Reason. This philosophy was developed by Algazzali and 

 Averroes. 



1106. Albucasis, a far-famed surgeon of Cordova, in- 

 vented and made use of excellent INSTRUMENTS, and did 

 not shrink from the performance of the most formidable 

 operations. Before him, the Arabs had already the lancet 

 (improved), the couching-needle, the probang, etc. He de- 

 scribed with great precision and detail complicated distilling 

 apparatus and their use. 



1126 1198. Averroes, one of the most famous men in 

 the world, was also a physician of great renown, although in 

 this capacity he must yield the palm to Avicenna ; but his 

 medical work " Colliget" had great weight too. Outside his 

 professional sphere he discovered the SUN-SPOTS, and ascribed 

 a cause to them just as probable as that which Sir W. 

 Herschel explained a century ago. It is, however, by his 

 COMMENTARIES on Aristotle that he deserved the high 

 reputation in which he was held for centuries. It was by 

 this work that his influence on Europe was felt most this 

 influence being at once profound and decisive. These two 

 great men, Avicenna and Averroes, were conversant with 

 every branch of knowledge, and by their correctness of 

 thought and breadth of view, they gave immense impetus 

 to the learning of the Middle Ages. Their intellectual 



