The last decade or so of the sixth century was a time of profound importance for western Christianity, but we should lose sight of much of the significance of these years if we were to look at them only in terms of Gregory the Great and Augustine's mission to the English. At about the time when Cassiodorus died, Gregory, then one of the seven deacons of Rome, was sent as papal representative to the court at Byzantium and it was there that he met the Spaniard Leander. Gregory went back to Rome to become abbot of the monastery where Augustine was already then or soon afterwards a monk, and Leander returned to Spain to become bishop of Seville c. 584. Augustine reached England in 597 and three years later Leander was succeeded in the bishopric of Seville by his brother, Isidore, on the walls of whose library there might be seen the effigies of Gregory and Leander side by side. That part of Spain to which Leander and Isidore belonged by adoption though not by birth, resembled Bede's part of Northumbria in the sense that both were frontier areas lying between two different cultural worlds. The Spanish conquests of Justinian's mercenaries which brought much of Baetica under Byzantine control stopped only a little short of Seville.