St Leo the Great, Pope & Doctor

A Tuscan native, Leo was elected Pope in 440 and reigned until his death in 461. 
Pope Benedict XVI termed his pontificate “undoubtedly one of the most important in the Church’s history.”  Leo was the first pope to be called “the great.”  He met Attila the Hun in 452 and persuaded him to turn back from his invasion of Rome.  (Alas, the city was pillaged by Vandals in 455.)  Leo was a significant theologian in his own right and also drew to his court many learned men, including Prosper of Aquitaine, a disciple of St Augustine of Hippo.  In a time of doctrinal disorder Leo was indefatigable in his repudiation of heretical sects. 
In 451, his doctrinal definition of Christ’s twofold nature (at once God and man), known as “Leo’s Tome,” was accepted by the Council of Chalcedon as definitive; the acclamation went forth at the Council that “Peter has spoken through Leo.”  Pointedly, however, Leo refused to confirm disciplinary proposals at the Council which seemed to make the Patriarch of Constantinople equal to the Pope of Rome.  For Leo, the office of Bishop of Rome was grounded in the special relationship between Christ and Peter, a relationship which could not be duplicated; therefore, Leo said, he depended on the mediation and example of St Peter in order to fulfil his duties.  

In a noteworthy Christmas sermon Leo exhorted “Christian, remember your dignity, and becoming a partner in the Divine nature, refuse to return to the old baseness by degenerate conduct.”  These words are echoed in the prayer at the Offertory of the Mass when wine and water are commixed in the chalice.