The chaste huntress Diana is shown in forest setting with her hunting dogs, Syrius and Phocion. A bow and quiver, also referring to the hunt, lie in front of them. Diana was an ancient Italian goddess of fertility and vegetation and was often associated with woods, hence she was also a goddess of hunting. She was also identified with Luna, the Italian moon goddess, and with the Greek goddess Artemis, no distinction being made between the two in terms of their attributes and powers. Artemis was revered as the everlasting virgin, an inaccessible maiden, an avid huntress, and the patroness of wild animals, of forests, hills and beasts. Under her special protection were pre-nubile girls and women in childbirth. She was thus the giver and taker of life.
Both mythological subjects and landscapes were popular genres in Cardinal Ottoboni's collection of paintings. Diana here occupies a grassy hill overlooking a sylvan setting in the Alban hills, an area some 60 miles south of Rome which was a favorite retreat of the Cardinal. Beyond lies the Mediterranean sea, situated between the forest and distant mountains, perhaps reminiscent of the Ligurian coast off Gaulli's native city of Genoa. The goddess seems to be resting while she gazes at a hunt underway in the middle ground below her, indicated by tiny, sketchy figures of maidens and animals, which include wild boars. Both of Diana's dogs are certainly individual portraits of household pets dear to the man who commissioned the painting.
Diana's reclining form is enhanced by the structure and color scheme of the composition. A strong diagonal divides the composition into triangular halves; Diana and the dogs are crowded together in the left foreground triangle. The warm, glowing palette is typical of Gaulli's later works, and the succession of color changes serve to separate and define the foreground, middle ground and background. The figure of Diana is bathed in light. The luminous quality of her white garment and rosy skin and of the white dog's pristine coat are set off by the deep blue of her cloak and the dark browns and greens of the forest vegetation, which in turn contrast with the pale, hazy blue of the distant sea and mountains. The strong, angular folds of Diana's garment, with crisp edges (often rolled over to reveal both the outer and the inner surface) is a stylistic development derived from the expressive sculptural forms of Gianlorenzo Bernini.