In the famous story told by Ovid, Philemon and his wife Baucis are a perfect expression of hospitality. As the story begins, Zeus and Hermes, disguised as mortals, are looking for shelter. All the other folk in the town refuse them. Only Philemon and Baucis are willing to take them in, sharing with them everything in their meager pantry, even being ready to kill their goose. The goose, however, runs away and leaps into Zeus' lap as a refuge. Zeus then explains that he is going to destroy the town and commands Philemon and Baucis to flee to the mountains for safety. They do as Zeus commands them; meanwhile, a flood then destroys the town, but the cottage of Philemon and Baucis survives and is transformed by the gods into a beautiful temple. As their reward, Philemon and Baucis are made the custodians of this temple and they are then honored by the gods in their death, being transformed into a pair of entwined trees.
You can find the story in Ovid's Metamorphoses, Book 8 - Latin and English. Meanwhile, in the painting, you can see the goose quickly making its way to the safety of Zeus' lap!