This vase painting depicts the famous moment in Homer's Odyssey when Odysseus, thanks to the help of the "moly" provided by Hermes, is able to thwart Circe's magic. She had turned Odysseus's companions into swine, but Odysseus is too much for her. The story is told in Book X of the Odyssey.
You can also find more myths and legends for the week of July 15-21 here. For more information and links to the actual javascript code, see the Myths & Legends Widget Reference Page.