He was a learned Benedictin abbot of a monastery called Agaliense, in a suburb of Toledo, promoted to the archbishopric of that city after the death of Eugenius, in December, 657, according to F. Flores; sat nine years and two months, and died on the 23rd of January, 667, according to the same learned author, in the eighteenth year of king Rescisvintho. His most celebrated work is a book on the Spotless Virginity of the Virgin Mary, against Helvidius, Jovinian, and a certain Jew: he breathes in it the most tender devotion to her, and confidence in her intercession with her Son. He had a singular devotion to Saint Leocadia, patroness of Toledo. Certain sermons of Saint Ildefonsus on the Blessed Virgin Mary, and some letters, are published by F. Flores. Some of his letters, which were first given us by D’Achery, were reprinted by cardinal D’Aguirre. In Spanish this saint is called Ildefonso, and by the common people Alanso, for Alphonsus, which is an abbreviation of Ildefonsus. See his short life by Saint Julian, bishop of Toledo, twenty-three years after his death. That by Cixila is not authentic. Flores reckons Saint Ildefonsus the thirty-first bishop of Toledo, from Saint Eugenius, the disciple of Saint Dionysius of Paris, whom, with the writers of his country, he counts the first in the year 112.
- Father Alban Butler. “Saint Ildefonsus, Archbishop”. , 1866. CatholicSaints.Info. 14 May 2016. Web. 4 December 2016. <>