Church of St. Peter in Chains, Rome, Italy

The artist observes the medieval tradition of picturing Moses with a pair of horns, but they are considerably shorter and less horn-like than in two-dimensional images of the period. The reason could be simply practical, in that projecting elements are more susceptible to breakage. Or it could be aesthetic. According to a number of internet sites, Michelangelo wrote that good sculpture should avoid projections, and the 16th century did see a retreat from literal horns to something more credible, such as the fly-away hair in this painting of 1515-20 or the light rays in this one from 1593.

Some have claimed that the stern sidewise glance in the statue replicates Moses' reaction to the golden calf in the Sistine Chapel's series on Moses (right). Readers may judge for themselves.

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Photographed at the church by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.