Post papes that invoke or suggest the sensation commonly known as "Sehnsucht"
Sehnsucht is an intense longing for somewhere you've never been, yet regard as your proper home. In this sense it is a type of nostalgia, but without a clear object of what you long for. To feel it in full force can be of such significance that ordinary reality may pale in comparison. Those who experience it will desire the bittersweet longing itself over most pleasures.

C.S. Lewis wrote extensively on it, called it different things and has some of best lines describing it.
>The longing for that unnameable something, the desire for which pierces us like a rapier at the smell of a bonfire, the sound of wild ducks flying overhead, the title of, The Well at the World’s End, the opening lines of Kubla Khan, the morning cobwebs in late summer, or the noise of falling waves.
>...our longing to be reunited with something in the universe from which we now feel cut off, to be on the inside of some door which we have always seen from the outside is... the truest index of our real situation.
>There arose at once, almost like heartbreak, the memory of Joy itself... The distance of the Twilight of the Gods and the distance of my own past Joy, both unattainable, flowed together into a single, unendurable sense of desire and loss... And at once I knew that to "have it again" was the supreme and only important object of desire.
>It might almost equally well be called a particular kind of unhappiness or grief. But it is a kind we want. I doubt whether anyone who has tasted it would ever, if both were in his power, exchange it for all the pleasures in the world.

There will be overlaps with other subject matter commonly on this board, but the common theme will demonstrate a character of its own over time, I think.