“The Greeks had a word, xenia—guest friendship—a command to take care of traveling strangers, to open your door to whoever is out there, because anyone passing by, far from home, might be God. Ovid tells the story of two immortals who came to Earth in disguise to cleanse the sickened world. No one would let them in but one old couple, Baucis and Philemon. And their reward for opening their door to strangers was to live on after death as trees—an oak and a linden—huge and gracious and intertwined. What we care for, we will grow to resemble. And what we resemble will hold us, when we are us no longer. . . .”