O. Henry often alludes to classical and Renaissance art while describing Behrman in "The Last Leaf." His description of Behrman’s appearance plays on tropes of antiquity and figures of the Italian Renaissance:
Old Behrman was […] past sixty and had a Michelangelo’s Moses beard curling down from the head of a satyr along the body of an imp.
Sculpted in the 16th century, Michelangelo’s statue of the Biblical prophet Moses is a famous work of Renaissance sculpture. It currently sits at the Church of San Pietro in Vincoli, Rome, and was famous in O. Henry’s era (Freud would write a famous essay on the sculpture in 1914). The sculpture is known for its penetrating gaze; it depicts Moses trying to restrain his anger after witnessing the worship of the Golden Calf. It is also noted for its extraordinarily long, tangled beard, which is the most explicit point of comparison with Behrman here.
But the allusion to this figure also illuminates certain aspects of Behrman’s personality. Like Michelangelo’s Moses, Behrman too is in possession of a fiery temper; his first reaction to Johnsy’s obsession with the last leaf is anger and irritation, and the narrator describes him as a “fierce old man” who rejects softness or sentimentality in others. Also like Michelangelo’s Moses, Behrman is infuriated by the superstition of those around him. Like the Israelites’ misplaced and ill-fated faith in the Golden Calf, Johnsy is putting her trust into the significance of a symbol that has no bearing or effect on reality; Behrman’s anger at this spurs him to action in the narrative.
Behrman is described as having the head of a “satyr.” A satyr is an imaginary creature depicted in Greco-Roman art as a mischievous, reveling woodland god with the head of a man, but the ears and lower body of a horse or goat. Behrman is also described as having the body of an “imp.” An imp is a similar creature from broader European folklore, also said to be physically small, playful, and mischievous. These allusions buoy the depiction of Behrman as a trouble-making, hard-drinking, but ultimately benevolent figure in the world of Johnsy and her friends.