Cornelio Musso, born in Piacenza in 1511, was a Franciscan monk and a renowned orator and homilist. He was made Bishop of Bitonto in 1544, delivered the inaugural oration at the Council of Trent (1545), and was sent as papal legate to the Holy Roman Emperor Ferdinand I in 1560. Musso died in 1574 and was buried in the Basilica of Santi Apostoli in Rome.

The reverse scene illustrates the legend that the horn of a unicorn can purify water from the poison of serpents, and refers here to Musso's work against corruptions in the Church. The shepherd tending his flock can be seen to represent Musso and his pastoral care.