John of Seville (Latin: Johannes Hispalensis or Johannes Hispaniensis) was the main translator from Arabic into Castilian together with Dominicus Gundissalinus during the early days of the Toledo School of Translators.
Some historians argue that in fact there were two different persons with a similar name, one as Juan Hispano (Ibn Dawud) and other as Juan Hispalense, this last one perhaps working at Galician Limia (Ourense), for he signed himself as "Johannes Hispalensis atque Limiensis", during the Reconquista, the Christian campaign to regain the Iberian Peninsula.
His three translations, the Secretum Secretorum dedicated to a Queen T[arasia?], a tract on gout offered to one of the Popes Gregory, and the original version of the 9th century Arabic philosopher Costa ben Luca's De differentia spiritus et animae, were all medical translations, intermixed with alchemy in the hispano-Arabic tradition. In his Book of Algorithms on Practical Arithmetic, John of Seville provides one the earliest known descriptions of Indian positional notation, whose introduction to Europe is usually associated with the book Liber Abaci by Fibonacci:
John of Seville translated the Arab astrologer Albohali's "Book of Birth" into Latin in 1153.[1]