Achelous is in flood, and Theseus cannot cross. They stay in his hall. Lelex, already gray, is the older man there. Pirithous laughs at a tale in which a god changes a shape. Lelex answers with a place he says he saw: an oak beside a linden, a low wall, the hills of Phrygia. The line is Metamorphoses 8.620.
Jupiter and Mercury come in disguise. A thousand doors stay shut. One opens. The roof is straw and marsh reed. Baucis and Philemon have grown old in that house, and they set out what they have.
They had one goose, the guard of that house. They meant to kill it for the guests. It was quicker than two old people, and it fled to the strangers. The strangers forbade the killing, and then they named themselves. The valley filled. The cottage became a temple. The two became the trees. The welcome did not stop the water.
a lime-tree and an oak, so closely grown their branches interlace
Brookes More, 1922, adds the interlacing. The Latin says they border. Neither sentence is the flood.
What remains is the wall, and the water.