E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Philemon and Baucis
entertained Jupiter and Mercury when everyone else refused them hospitality. Being asked to make a request, they begged that they might both die at the same time. When they were very old, Philemon was changed into an oak, and Baucis into a linden tree. (Ovid: Metamorphoses, iii. 631, etc.)