The active minds of these gifted scholars enabled them to master at the same time the most complicated problems of widely different branches of scientific knowledge. The difficulty and novelty of the subject were always the strongest incentives to their industry. The study of jurisprudence enjoined by their law, as a religious duty, was always entered upon in the beginning of their literary career, no matter to what professions they were subsequently to be devoted. Rabbi Hasdai-ben-Schaprut wrote a commentary on the botanical treatise of Dioscorides, of which he had made an Arabic version; Rabbi Judah, who lived under Abd-al-Rahman III., was renowned for his acquaintance with both Hebrew and Arabic literature; Joseph translated the Talmud for Hischem II.; Manasseh-ben-Baruch compiled a critical lexicon, a colossal monument of patience and erudition. To Isaac-ben-Chanan is ascribed the rendering into classic Hebrew of the complete works of Aristotle. Isaac Alphes codified the laws of the Talmud; Samuel-ben-Alarif, the minister of Habus, King of Granada, renowned alike as statesman, astronomer, and poet, composed a panegyric of his sovereign in seven languages. Moses-ben-Ezra wrote poems which disclose instructive scenes of mediæval life and manners; the grammatical works of Judas-ben-David were recognized as authoritative wherever the Hebrew tongue was spoken; Isaac-ben-Baruch was one of the most learned and accomplished mathematicians of his time. In addition to these names, famous in the history of letters, the Hebrew community of Spain included poets like Judas Levi, whose works, translated into Arabic and Latin, obtained a wide and deserved popularity; astronomers like Ben-Chia; geographers like Isaac Latef; physicians like Charizi; travellers like Benjamin of Tudela, whose writings may still be perused with pleasure and advantage; natural philosophers like Solomon-ben-Gabirol, who had the rare faculty of clothing scientific conceptions in poetical language; universal geniuses like Moses-ben-Maimon and Ben-Ezra, whose talents illustrated and embellished every subject within the realm of human knowledge. Not less noted were the Jewish physicians, who did not, however, exist as a distinctive profession, their commanding abilities being also displayed in other departments of literature and science.