Dissatisfied with the meager philosophies of his Italian teachers, Gherardo went to Toledo before 1144. There he learned Arabic, initially so that he could read Ptolemy's Almagest, which retained its traditional high reputation among scholars, even though no Latin translation existed. Although we do not have detailed information of the date when Gherard went to Spain, he was certainly there by 1144.
Toledo, which had been provincial capital in the caliphate of Cordoba and a seat of learning, was safely available to a Catholic like Gerard. Since it had been conquered from the Moors by Alfonso VI of Castile, Toledo remained a multicultural capital. Its rulers protected the large Jewish colony, and kept their trophy city an important centre of Arab and Hebrew culture, one of the great scholars associated with Toledo being Rabbi ben Ezra, Gerard's contemporary. The Moorish and Jewish inhabitants of Toledo adopted the language and many customs of their conquerors, embodying Mozarabic culture. The city was full of libraries and manuscripts, the one place in Europe where a Christian could fully immerse himself in Arabic language and culture.
In Toledo Gerard devoted the remainder of his life to making Latin translations from the Arabic scientific literature.
Gerard's translations:
Gerard of Cremona's Latin translation of an Arabic text was the only version of Ptolemy’s Almagest that was known in Western Europe for centuries, until George of Trebizond and then Johannes Regiomontanus translated it from the Greek originals in the 15th century. The Almagest formed the basis for a mathematical astronomy until it was eclipsed by the theories of Copernicus.
Gerard edited for Latin readers the Tables of Toledo, the most accurate compilation of astronomical data ever seen in Europe at the time. The Tables were partly the work of Al-Zarqali, known to the West as Arzachel, a mathematician and astronomer who flourished in Cordoba in the eleventh century.
Al-Farabi, the Islamic "Second teacher" after Aristotle, wrote hundreds of treatises. His book on the sciences, Kitab al-lhsa al Ulum, discussed classification and fundamental principles of science in a unique and useful manner. Gerard rendered it as De scientiis (On the Sciences).
Gerard translated Euclid’s Geometry and Al-Farghani's Elements of Astronomy.
Gerard also composed original treatises on algebra, arithmetic and astrology. In the astrology text, latitudes are reckoned from Cremona and Toledo.
External links
Some of the works credited to Gerard of Cremona are probably the work of a second Gerard Cremonensis, more precisely Gerard de Sabloneta (Sabbionetta) (ca 13th Century) His best work translated Greek/Arabic medical texts, rather than astronomical ones, but the two translators have understandably been confused with one another. His translation from works of Avicenna is said to have been made by order of the emperor Frederick II.
Other treatises by the "Second Gerard" include the Theoria or Theorica planetarum, and versions of Avicenna’s Canon of Medicine— the basis of the numerous subsequent Latin editions of that well-known work — and of the Almansor of al-Razi {("Rhazes" in Latin-speaking Europe), which might have revolutionized European medical practices, if it had been more widely read.