Zeus and Hermes came disguised as ordinary peasants, and began asking the people of the town for a place to sleep that night. They had been rejected by all, “so wicked were the people of that land,” when at last they came to Baucis and Philemon’s simple rustic cottage. Though the couple was poor, their generosity far surpassed that of their rich neighbours, among whom the gods found “doors bolted and no word of kindness.”
After serving the two guests food and wine (which Ovid depicts with pleasure in the details), Baucis noticed that, although she had refilled her guest’s beechwood cups many times, the pitcher was still full (from which derives the phrase “Hermes’s Pitcher”). Realising that her guests were gods, she and her husband “raised their hands in supplication and implored indulgence for their simple home and fare.” Philemon thought of catching and killing the goose that guarded their house and making it into a meal, but when he went to do so, it ran to safety in Zeus’s lap. Zeus said they need not slay the goose and that they should leave the town. This was because he was going to destroy the town and all those who had turned them away and not provided due hospitality. He told Baucis and Philemon to climb the mountain with him and Hermes and not to turn back until they reached the top.
After climbing to the summit (“as far as an arrow could shoot in one pull”), Baucis and Philemon looked back on their town and saw that it had been destroyed by a flood and that Zeus had turned their cottage into an ornate temple. The couple’s wish to be guardians of the temple was granted. They also asked that when time came for one of them to die, that the other would die as well. Upon their death, the couple were changed into an intertwining pair of trees, one oak and one linden, standing in the deserted boggy terrain.
Source: Baucis and Philemon – Wikipedia