St. Isidore who succeeded his brother St. Leander as Archbishop of Seville, was one of the great bishops of the seventh century. He was proficient in all branches of knowledge and was regarded as one of the most learned men of his time; with Cassiodorus and Boethius he was one of the thinkers whose writings were most studied in the Middle Ages. St. Isidore died in 636. Pope Innocent XIII canonized him in 1722 and proclaimed him a Doctor of the Church.