A couple of friends just happened to fall into a discussion somehow about the "horned Moses" by Michelangelo. (Happens all the time, right?)
So they asked me, their Hebrew philologist friend, to explain the matter.
In the course of tackling the story in an email to them, I struck upon what I believe is a new solution to this long-standing linguistic puzzle.
The issue, in short, is that Exodus 34:29, 30, and 35 state that "the skin of Moses' face קָרַן (qaran)." And קָרַן (qaran) here is a verb meaning... Well, we don't know. Because it only occurs in this single passage. We do have a very common noun from this root, קֶרֶן (qeren), meaning 'horn'.
But as a verb, we have no context to determine the meaning. The rest of the passage describes that Moses, as result of whatever it was that קָרַן (qaran) meant, would wear a veil ( מַסְוֶה [masveh]) over his face. He would take off the veil when he spoke to God, but put it back on when in front of the Children of Israel. He did this because "the skin of Moses' face... קָרַן (qaran)."
Already in ancient times, these verses were generating confusion. The Greek Septuagint translation offers an interpretation when it renders the verb as δεδόξασται (dedoxastai), "was glorified."
St. Jerome translates the root based on the Hebrew noun and gives us the "horned face" (faciem...cornutam) which is the basis of Michelangelo's famous statue.
Another ancient interpretation, generally followed in modern translations, is to view this as a verb meaning "to shine." This seems to have support in the use of the root in Habakkuk 3:4, where we read, "His radiance is like light, he has two rays coming from his hand." The word rendered as "rays" there is קַרְנַיִם (qarnayim), lit. 'two horns'. Perhaps this means bolts of lightning, which could resemble horns. So if this verb means something like "to send out rays" then we can translate the passage as "the skin of Moses' face shone."
Sorry, I really did intend that to be short when I started typing. But the academic in me just had to be comprehensive.
This brings me to my new theory. While examining this matter, I spent some time considering a possible interpretation based on the same root in Arabic. This root primarily means "to connect, join." This gives us common words such as مقارنة (muqaarana), 'comparison', and قرينة (qarina), 'wife' (i.e., joined one). The root also provides the same common noun as Hebrew, the Arabic word قرن (qarn) means 'horn'.
But I was intrigued to discover that this verbal root in Arabic, in the Form X derivation, has the meaning "to produce pus", "to come to a head (of boils)."
We must always use caution when comparing the Hebrew and Arabic languages. But these languages are at least as related as, say, French and Italian. So a meaning in Arabic can be a valid window into the meaning of the same root in Hebrew.
This raises the startling possibility that the Hebrew קָרַן (qaran) meant something like "to break out in boils" or "to run with pus." Indeed, it must be noted that the Hebrew text specifically describes this as something happening to Moses' skin ( עֹור ['or]).
This could also explain more directly why Moses is covering his face with some type of cloth when not in the presence of God. In addition to this condition possibly being a disfigurement, it required a cloth to treat the symptoms.
Exodus 34:30 states that the people "were afraid to draw near to [Moses]" because the skin of his face קָרַן (qaran). It is more likely that they were afraid to draw near to him because of a concern of catching what he had or because of revulsion at the sight of his condition. If his face was shining, they would have been afraid, to be sure. But the text specifically states that they were afraid "to draw near to him" (מִגֶּשֶׁת אֵלָיו). This indicates fear of being near him, which was more likely as a result of a condition than merely his appearance.
It may be that this root meaning is what generates the meaning of 'horn'. A pastoral people certainly knew that animals are not born with horns. The horns sprout out of buds on the head much as a boil will mature and then produce a white surface before breaking.
At any rate, I'm not aware of anyone previously proposing this solution on the basis of the Arabic root. This interpretation has the virtue of explaining the overall passage at least as well as a meaning "to shine." It also has cognate language support. But the clincher is that this solution alone accounts for the reality that קָרַן (qaran) was affecting Moses' skin specifically. Elsewhere in the Bible, it is just faces themselves that shine, not the skin on them! (cf. Numbers 6:25; Matt 17:2)
By the way, if you are in Rome, you can find Michelangelo's beautiful statue at an equally beautiful Church, St. Peter in Chains, just north of the Coliseum. Per Canon Law, there is no admission fee.