Caravaggio's David with the Head of Goliath

Giorgio de Chirico, turning away from the surreal landscapes and abstract forms of his great period, went for refreshment to mythology, as in his 1940 painting "The Boar Hunt." That's how I started out. But because I am not permitted to show it here, I   shall turn to my favorite Caravaggio, "David with the Head of Goliath," from the Galleria Borghese in Rome, a painting full of allegorical possibility. Is David the model? Is Goliath the painter? -- DL