LITERATURE OF THE ARABS. 93 



pounds' weight of gold to engage in his service the 

 famous mathematician Leo of Constantinople, who 

 was then employed by the Emperor Theophilus in 

 delivering lectures and establishing schools in his 

 capital. But the invitation was declined ; as the 

 Greeks, from a foolish vanity of their superior ex- 

 cellence, were jealous of imparting to heathen the 

 sacred fire of their learning. Ibn Korrah enriched 

 the literature of his country with translations of 

 Archimedes and the Conies of ApoUonius. But 

 none of them seem to have bequeathed to the world 

 any treatises of importance ; and, at the revival of 

 letters in the fifteenth century, this branch of the 

 science is said to have been found nearly in the 

 state in which it was left by Euclid. Brucker, in 

 his History of Philosophy, maintains that the Sara- 

 cens owed their mathematical knowledge solely to 

 the Greeks, and that the study made no progress 

 w^hatever in their hands. But later writers, par- 

 ticularly Montucla, have done ample justice to their 

 researches in certain departments of this sublime 

 science. 



Trigonometry derived from the Arabs the form 

 which it still retains. They substituted the use of 

 sines for that of the chord, which had been employed 

 by the ancients. Ibn Musa and Geber composed 

 original works on spherical trigonometry ; and Al- 

 kendi, besides his own treatise, De Sex Quantitatihus, 

 translated that of Autolycus, De Sphara Mota. Al- 

 gebra, though not the invention of the Saracens, 

 received valuable accessions from their talents ; 

 and, on comparing them with their predecessors, 

 their advances will perhaps be found as conspicuous 

 as the improvements which have been suggested 

 and the progress that has been made by later and 

 even by modern proficients. Ibn Korrah and Ibn 

 Musa are the earliest Arabian mathematicians who 

 have treated on this science. The former wrote 

 on the certainty of the demonstrations of the 



