This shows the famous punishment of Prometheus: he had angered Zeus by violating Zeus' orders and choosing instead to give the gift of fire to man; for this defiance, Zeus chained Prometheus to a rock and sent an eagle to gnaw at his liver. Each day, the liver would grow back and the eagle would return once again to the feast. In some versions of the story, Hermes was the god charged with carrying out Zeus' orders, and you can see Hermes shown here in the background of the painting.
You can also find more myths and legends for the week of May 13-19 here. For more information and links to the actual javascript code, see the Myths & Legends Widget Reference Page.