I was visiting one of Madrid’s great museums back in February 2005 and came upon a painting of Moses the Law Giver. As I recall, he was holding the Ten Commandments and sprouting horns.
The Madrid painting seemed awfully anti-Semitic — even by 15th century Spanish standards. I asked around and nobody at the museum could explain why Moses had horns.
The painting continued to mystify me. Until today. Reading Christianity: The First Three Thousand Years, by Diarmaid MacCulloch, I learned how Moses got his horns. Apparently, St. Jerome gave them to him.
The translator of the Vulgate version of the Bible misinterpreted a Hebrew word in the book of Exodus. Instead of saying that Moses’ face “shone” after his descent from Mt. Sinai, the Vulgate said that Moses’ face “had horns.”
(The Jewish Encyclopedia offers more details.)