The most prolific and influential translator of the Middle Ages: based at the Toledo School of Translators between 1144 and 1187, Gerard of Cremona translated between 74 and 87 works from Arabic into Latin, leading a workshop of native collaborators. He translated directly from Arabic works such as Al-Khwarizmi's algebra and Ibn Sina's Canon of Medicine — Europe's reference medical text until the 17th century — as well as Al-Zahrawi's Kitab al-Tasrif and works by Al-Razi. He also rendered into Latin, via intermediate Arabic versions, Greek classics such as Ptolemy's Almagest, Euclid's Elements, and Aristotelian treatises.