Almagest

Almagest is the Arabic name of an astronomical treatise explaining the motions of the stars, originally written in Greek as Hè Megalè Syntaxis by Ptolemy of Alexandria, Egypt, sometime around the 2nd century, and accepted for over a thousand years by the vast majority of people in Arabic and European societies to be the correct cosmological model. Although it was never lost to Islamic scholars, the Almagest was lost to early medieval Europe, dimly remembered in astrological lore. It was recovered in Toledo by Gerard of Cremona in the 12th century and translated into Latin from Arabic. This was the form in which the Ptolemaic system was known in the European High Middle Ages.

In the 15th century a new translation, this time directly from the Greek, with a commentary as long as the original work, was completed ca 1481 by George of Trebizond, called "a Cretan emigré" in the records of the Papal Curia. In the early Renaissance, the library of the Curia became a center for the study of Greek scientific manuscripts, which were sometimes older and more accurate than their Latin counterparts.

The work of translation, done under the patronage of Pope Pope Nicholas V was intended to supplant the old translation. The new manuscripts were a great improvement; the new commentary was not, and aroused much heated criticism. The Pope declined the dedication of the translation. But a German astronomer, Johannes Regiomontanus ("Johann Königsberg"), a protege of the brilliant Greek churchman Johannes, Cardinal Bessarion, came to Italy with his patron, learned Greek, and produced a full-scale "Epitome" of Ptolemy's work, from which most astronomers learned their art for the next century and more.