Philosophy of Botany. 215 



about in a very short time a conflux of enterprising people and 

 rapid growth of industries, trade, and science. After the lapse 

 of two hundred years, during the reign of Abd-Errahman III. 

 (912-961), Spain had become the most prosperous empire, 

 with a population of 30,000,000, emulating Rome in the Au- 

 gustan time. Abd-Errahman was the first Spanish Omajade 

 who declared himself independent from the Oriental Khalifat. 

 From authentic documents we are informed that there existed 

 seventy large libraries and seventeen great schools, provided 

 with liberal endowments, elegantly furnished in palatial build- 

 ings. Students from distant Anglia, Germany, and France 

 flocked to the celebrated universities of Cordova, which num- 

 bered one million inhabitants; to Toledo, Granada, and Sevilla 

 to listen to the lectures of Averrhoes, of Cordova, the chief 

 commentator of Aristotle ; Albucasis, the surgeon ; Alhazen, 

 the astronomer, who discovered the refraction of the atmos- 

 phere ; Almaimon, who determined with nearly complete ac- 

 curacy the obliquity of the ecliptic ; Ben Musa, who intro- 

 duced the Indian numerals and invented the common method 

 of solving the quadratic equations. The works of Aristotle, 

 Theophrastus, and Dioscorides were translated and taught in 

 the schools. 



Alhazen was the first to correct the Greek misconception as 

 to the nature of vision ; determined the retina as the seat of 

 sight, and showed that the impression was carried by the optic 

 nerve to the brains. Many instances in physics are not better 

 explained nowadays than they were by him. The materia 

 medica was expounded in well-arranged pharmacopci'ias. No 

 branch of art or science known at this period was neglected, 

 and advancement loomed up in the theoretical field as well as 

 the practical. This effulgent radiancy, however, found its 

 counterpoint in the dark shadow of extravagant luxury, effem- 

 inating sensuality weakening the national valor. Wisdom 

 and mental acumen sunk to scholastic flippery; fatuous spec- 

 ulations and that trifling witticism to which the Arab, by 

 national propensity and a spirit of language, is much addicted, 

 and which found abundant fuel in the now prevailing religious 

 discussions. 



The eastern Khalifat had already fallen into a tottering atti- 



