Landscape with Hercules and Cacus

Cacus was one of the local deities or heroes of Rome. He was believed to be the son of Vulcan, had three heads, and could breathe out fire (fun!). He lived on the Aventine Hill in a cave. When Hercules was returning from one of his expeditions, he brought with him oxen, which he had stolen from Geryon. He let them graze freely, while he himself was having a rest. Cacus stole some of the oxen and hid them in his cave. When Hercules found that out, he fought a battle with Cacus and won. Poussin usually painted landscapes with a mythological subject in the background.