Isidore was born in Cartagena, Spain, to an influential family: his brother Leander immediately preceded him as archbishop of Seville, his younger brother was also a bishop, and their sister was an abbess in charge of forty convents. Isidore was an enthusiastic and apt student, who mastered Greek and Hebrew. His own Latin is affected by local Visigothic traditions and contained hundreds of recognizably Spanish words; the scholar Arevalo identified 1640 of them. At a time of disintegration of classical culture, and aristocratic violence and illiteracy, he assisted Leander in the conversion of the Visigoth Arians to Catholicism. He also presided over the Synod of Seville (619), and the Fourth Council of Toledo (633), which required all bishops to establish seminaries, on the pattern of the one at Seville associated with Isidore.
His most important work was his encyclopedia, the Etymologiae. The work takes its title from just one of its twenty constituent books, a highly fanciful account of the etymologies of words, more revealing as a folk etymology of his age. The encyclopedia as a whole was a huge compilation in 448 chapters, devoted to transmitting a condensed epitome of the learning of antiquity. The depository of classical culture in Isidore's compendium was so highly regarded that in a great measure it superseded the use of the individual works of the classics themselves, and many were not recopied and are lost. The book not only was one of the most popular compendia in medieval libraries but was printed in at least 10 editions between 1470 and 1530, showing Isidore's continued popularity in the Renaissance. Until the 12th century brought translations from Arabic sources, Isidore transmitted what western Europeans remembered of the works of Aristotle and other Greeks. This work was much copied, particularly in the medieval bestiary.
His other works include his Chronica Majora (a universal history), De differentiis verborum (a book of synonyms), a History of the Goths, On the Nature of Things, and Questions on the Old Testament.
See also: Cartographer