About 825, al-Khwarizmi wrote an Arabic language treatise on the Hindu–Arabic numeral system, which was translated into Latin during the 12th century. The manuscript starts with the phrase "Dixit Algorizmi" ('Thus spake Al-Khwarizmi'), where "Algorizmi" was the translator's Latinization of Al-Khwarizmi's name. Al-Khwarizmi was the most widely read mathematician in Europe in the late Middle Ages, primarily through another of his books, the Algebra. In late medieval Latin, "algorismus", English 'algorism', the corruption of his name, simply meant the "decimal number system". In the 15th century, under the influence of the Greek word ἀριθμός ("arithmos"), 'number' ("cf." 'arithmetic'), the Latin word was altered to "algorithmus", and the corresponding English term 'algorithm' is first attested in the 17th century; the modern sense was introduced in the 19th century.