Yes, I know, it is only an optional memory, but I like him. Plus, he has been proposed as one of the patron saints of the internet. Why is he important? What did he do?
He is a doctor of the church, and there are not so many. His two brothers were also bishops and one of them also a canonized saint. He converted the Visigothic King of Spain.
He presided over the Council of Toledo (633), where long before the Council of Trent, already recommended to have seminaries in all cathedrals. Education was St. Isidoro’s priority.
He can be considered the last native speaker of Latin, but encouraged the study of Greek and Hebrew and made provisions for it to be implemented all over the kingdom.
Before the Arabs, followed by the Dominicans who incorporated Aristotle into Christianity, it was St. Isidore who appreciated and encouraged the study of Greek philosophy, specially, Aristotle.
His most celebrated work was the world’s first encyclopedia, The Etymologies, which comprises 20 volumes and 10 editions from 1470 to 1530, well into the Renaissance era. There he taught that the earth is round and in his latter writings he made it clear that he understood that as globular, not circular.
Some say he was undoubtedly the most learned man of his age and the 8th Council of Toledo remember him as “The extraordinary doctor, the latest ornament of the Catholic Church, the most learned man of the latter ages, always to be named with reverence, Isidore”.