Nostalgia is, semantically, a pain.
I've never been one for going back to the old school or college: it's someone else's turn now, and who wants to live in the past?
But just recently my closest friend at university contacted me out of the blue (the wonders of the internet), and we had a pleasant lunch and catch-up conversation. As is the way of things, there turned out to be more than a few points of near contact and mutual acquaintance in our more recent lives.
So that wasn't at all painful; but in hunting out old photographs, I came across all sorts of paperwork, including a diary I kept in my last year at school. Naturally, I was mystified at quite a few of the names and other references in it (clearly I thought I would always know what I meant); but there was no mystery about the self-important, over-anxious, busy-busy, whiny White Rabbit of an eighteen-year-old writing it. Nor about the hints and portents - all too obvious now - of all the what-ifs, might-have-beens, indecisions and wrong turnings of all the years since.
Ouch. Not just a semantic pain.