John of Seville

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John of Seville (Latin: Johannes Hispalensis or Johannes Hispaniensis) was a twelfth-century translator, perhaps however working at Galician Limia (Ourense), for he signed himself "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: “A number is a collection of units, and because the collection is infinite (for multiplication can continue indefinitely), the Indians ingeniously enclosed this infinite multiplicity within certain rules and limits so that infinity could be scientifically defined; these strict rules enabled them to pin down this subtle concept.”