I keep coming back to this beautiful New Yorker piece by Kathryn Schulz. An excerpt:
"All of this is made more precious, not less, by its impermanence. No matter what goes missing, the wallet or the father, the lessons are the same. Disappearance reminds us to notice, transience to cherish, fragility to defend. Loss is a kind of external conscience, urging us to make better use of our finite days. As Whitman knew, our brief crossing is best spent attending to all that we see: honoring what we find noble, denouncing what we cannot abide, recognizing that we are inseparably connected to all of it, including what is not yet upon us, including what is already gone. We are here to keep watch, not to keep."