Ildefonsus was from a Toletan family. As a young man he was educated in the monastery of Agali, then he was ordained a deacon in Toledo by Bishop Helladius (he writes about these events in his own work De viris illustribus). In AD 657, after the death of Eugenius II, Ildefonsus became a bishop of Toledo at the instigation of King Reccesvinth (reigned 653–72). He died in 667. He wrote De cognitione baptismi during his episcopacy. Along with the passage 2.21–27 from Isidore`s of Seville De officiis it is the most important document of the baptismal practice in the seventh-century Spain. For more detailed information on the text see Robles 1970, and Yarza Urquiola 2007: 278–333.