According to an inscription of the back of the former mount, transcribed in the 1986 Christie's catalogue, the drawing illustrates the incident in Book 3 of the Aeneid: 'The Embarcation of Aeneas from Crete, to go the the Coast of Italy. When after a Tempest of three Days and Nights the Trojans land in the Isles of Strophades, where the Harjoies dwelt - A description of the Harpies and the Trouble they give to the Trojans! The Trojans, having discovered unguarded castle and goats on landing on the islands (south of Zante off the west coast of the Peloponnese), slaughtered them and prepared a feast to Jupiter, whereupon the Harpies, birds with faces of girls, with filth oozing from their bellies, with hooked claws for hands and faces pale with an insatiable hunger, fell upon the food, tearing it to pieces and polluting everything with their food contagion. The Trojans then relaid their feast under an overlaying rock but were attacked again, whereupon Aeneas ordered his men to arm themselves. The Harpies finally flew off, but not until one of them cursed the Trojans in the name of Apollo (see D. West, transl., Virgil: The Aeneid 1991 ed., pp. 63-4.

Three subjects from the Aeneid were exhibited at the Free Society in 1769 in all, the other two being no. 185, 'Aeneas carrying his father Anchises from the Crowning of Troy', and no. 187, 'Aeneas the Sybil entreating the shades to visit his father Anchises'. Similar drawings are at Stourhead (see Michael Rysbrack, exhibition catalogue, Bristol Art Gallery, March-May 1982, nos. 93-4, 96)