I BOY BITTEN BY A LIZARD by Caravaggio (c 1594-5)

Look for: Dirty fingernails

Caravaggio’s painting of a boy jumping back from a lizard’s bite may be a portrait of his regular model Mario. The tiny assailant is barely visible amid the objects in the foreground: roses in a glass carafe, scattered fruit. This “still life” forms a tranquil contrast to the histrionic recoil of the boy. The light – and the dramatic focus – have landed on his face and naked shoulder.

The work is one of two nearly identical versions of the same subject. There is a covert reference to a famous ancient Greco-Roman statue, that of the Apollo Sauroktonos (or “Apollo the lizard killer”). Copied numerous times in antiquity,

the composition is thought to have originated with the 4th-century Greek sculptor Praxiteles, a master of sensuous and naturalistic depiction. The “original” version is long lost, but surviving examples typically show the youthful, nude god about to kill a poisonous salamander.

Caravaggio, however, has flipped the roles, turning a moment of high mythic drama into a banal mishap. The lizard leaps up to bite the Apollonian boy, provoking one of the most petulant scowls in the history of art.

John Ruskin, who saw in Caravaggio a “perpetual seeking for and feeding upon horror and ugliness, and filthiness of sin”, was one of successive critics who have objected to the earthy, ribald nature of Caravaggio’s imagery. For others, though, the lack of idealisation is the point. The artist showed the dirt beneath his models’ fingernails, the shadows under their eyes. He refused to quell eroticism. There is a tension, often, between the narrative role – the Biblical or classical persona – and the reality of the model who poses.

In his avant-garde film of 1986, Caravaggio, Derek Jarman played upon this tension. He restaged compositions by Caravaggio with meticulous attention to lighting and pose, and yet there’s something deliberately, comically clunky about the recreated scenes. They revel in their own artifice. You can almost sense the actors about to break into laughter at the incongruity of it all.

James Cahill’s novel ‘Tiepolo Blue’ (Sceptre, £14.99) is out on June 9