A lot of Spanish theologians and Church fathers are awfully fond of quoting St. Gregory the Great. But then, a lot of theologians from everywhere are fond of quoting him. So it didn’t stand out to me when St. Beatus of Liebana quoted him all over.
However, it turns out that when the pope sent St. Gregory the Great as his envoy to Constantinople (back when he was just another monk/abbot of Senatorial family and great learning), St. Greg met up with another visitor to Constantinople, St. Leander of Seville. They hit it off, and it was St. Leander who pressed St. Gregory to write his famous book on the moral interpretation of the Book of Job (Moralia on Job).
So they stayed in touch, and St. Leander made sure he got copies of all of St. Greg’s books. When St. Greg became pope, he kept sending his new books over to Seville.
And St. Leander of Seville was the older brother (and predecessor as Bishop of Seville) of St. Isidore of Seville, the great medieval teacher.
So since St. Leander and St. Isidore pushed St. Gregory, and since they made copies of his work available, everybody else in Spain also got well-versed in the works of Pope St. Gregory the Great.
Pretty neat, huh?