A 12th-century English Arabist known as Robertus Castrensis, Robert of Chester built his translating career in mid-12th-century Christian Iberia. In Segovia he completed the first Latin translation known of an Arabic alchemical treatise (1144) and, in 1145, the first Latin version of al-Khwarizmi's algebra (Liber algebrae et almucabola), which introduced the term "algebra" into Western vocabulary and gave rise, via its opening line "Dicit Algoritmi", to the modern term "algorithm". He also completed, with Pedro the Venerable's commission, the first Latin translation of the Quran (1143).