The subject of the painting is a scene from the opera Issé by Houdar de la Mothe. The opera is about the nymph Issé (also known as Amphissa), daughter of Macareus and grand-daughter of Aeolus, who falls in love with the shepherd Philemon, who is actually
Apollo in disguise. An oracle warns her that Apollo wants to claim her as his mistress, but she resolves to stay true to Philemon. Apollo then reveals who he truly is. The picture illustrates Apollo discarding his shepherd’s disguise to reveal his true identity to Issé