In Cities of the Plain, in a conversation between an aging man and a young cowboy, Cormac McCarthy writes:
...There's hard lessons in this world. [says the old man]While this is unmistakably true, it's not really complete. All the things that we miss once they have passed away would simply become garish and monstrous if they remained forever. An end is perhaps the greatest (and most painful) blessing we have been given. Even the loveliest piece of music or the most delicate flower would become nauseating and dull if it continued indefinitely.
What's the hardest? [replies the cowboy]
I don't know. Maybe it's just that when things are gone they're gone. They aint comin back.
At the end of Le Petit Prince, Antoine de Saint-Exupery writes, "Ca c'est pour moi, le plus beau et le plus triste paysage du monde. C'est le même paysage que celui de la page précédente, mais je l'ai dessiné une fois encore pour bien vous le montrer. C'est ici que le petit prince a apparu sur terre, puis disparu. [That is for me the loveliest and the saddest landscape in the world. It is the same landscape as the preceding page, but I drew it a second time so you could see it well. It is here that the little prince appeared on earth, then disappeared.]" The landscape is beautiful, not just in itself, but because of what transpired there. All good things must end, but because they end, they stay beautiful.