From the Wikipedia: The marble sculpture depicts Moses with horns on his head. This was the normal medieval Western depiction of Moses, based on the description of Moses' face as "cornuta" ("horned", though other meanings are possible) in the Latin Vulgate translation of Exodus 34:29-35 [2]. The Greek Septuagint and Hebrew Masoretic texts use words meaning "radiant", suggesting an effect like a halo, though it has been argued that the Hebrew text remains unclear as to the original sense intended. Horns were symbolic of authority in ancient Near Eastern culture, and the medieval depiction had the advantage of giving Moses a convenient attribute by which he could easily be recognized in crowded pictures.

According to Giorgio Vasari in his Life of Michelangelo, the Jews of Rome came like "flocks of starlings" to admire the statue every Shabat.

And from the Enc. Brittanica, concerning Michelangelo: As soon as the [Sistine] ceiling was finished, Michelangelo reverted to his preferred task, the tomb of Pope Julius. In about 1513–15 he carved the Moses, which may be regarded as the realization in sculpture of the approach to great figures used for the prophets on the Sistine ceiling. The control of cubic density in stone evokes great reserves of strength; there is richer surface detail and modeling than before, with bulging projections sharply cut. The surface textures also have more variety than the earlier sculptures, the artist by now having found how to enrich detail without sacrificing massiveness.