8 4 MATHEMATICAL SCIENCES. 



The exact sciences continued to be taught and to make progress amongst 

 the Greeks, the Eastern peoples, and the Arabs hi Spain. Astronomy was 

 still the favourite science in the Mussulman schools, and the wise men of 

 Islam were always drawing up astronomical tables. Al-Battany spent fifty 

 years of his life upon his Sabean Table ; Aben Byhan (died in 941), 

 Mohammed al-Saghany (died in 989), Absoufy and Aboul-Waffa (at the end 

 of the tenth century), and the most celebrated of all these philosophers, 

 Aly ben Abdel-Rhaman, spent their whole existence in drawing up different 

 astronomical tables, calculating according to the laws of the motion of the 

 stars, for astronomy was at that time a science rather of calculation than of 

 observation. The Spanish schools (Figs. 59 and 60) were not behindhand 

 with the academy of Bagdad and the school of Alexandria, although the 

 scientific celebrities in them were not so numerous in the eleventh as they 

 had been in the tenth century. The most famous of these Arab savants 

 were Spanish Jews : such as Soliman ben Gavirol (died in 1070), who was not 

 less distinguished as a poet and moralist than he was as a mathematician, and 

 Abraham ben Chija, who at about the same period drew up a Celestial 

 Cosmography which was held in high repute for more than six centuries. 

 The rabbis who were most famous for their mathematical and astronomical 

 works, written in Arabic, such as Ibn-Zarcali, Abraham Arzachel, Aben-Ezra, 

 all more or less mingled with the theorems and calculations which they took 

 from the exact sciences fanciful deductions from the Talmud. 



Astronomy in those days was very often no more than astrology ; that is 

 to say, the art of drawing horoscopes and making predictions by a study of 

 the position of the stars and of the mutual relations of the planets. The 

 Eastern peoples, Persians, Arabs, Jews, were much addicted to these practices. 

 They endeavoured to ascertain the future by means of the celestial con- 

 junctions, and believed that they could read in the heavens not only the 

 fate of empires, but the destiny of all human beings. This so-called 

 philosophical doctrine was inaugurated in the ninth century by the Arab 

 astrologer Albumazar, in his book on the Great Conjunctions. He asserted 

 that the appearance of the prophets and of religions had coincided with the 

 conjunctions of the planets. Thus, according to him, the conjunction of 

 Jupiter with Mercury produced the Christian law ; but, in a given time, the 

 conjunction of the Moon with Jupiter would bring about the total downfall 

 of all religious beliefs. A doctrine such as this, as insane as it was impious, 



