It feels like an odd ache: an insatiable longing for something that you can't exactly place and that you can never be certain is real.
I remember the first time I became consciously aware of my tendency toward nostalgia. I was around 23. I was driving in a car, probably coming home from a show. I began to feel that I was becoming older and I feared that I was losing my grip on something.
Perhaps nostalgia is a kind of fear.
On one hand, that ache associated with nostalgia is rather painful and provokes a profound sense of terror. On the other, the fact that it has persisted, in very much the same form, for so many years, suggests to me that whatever it is that I fear losing my grasp on is not anything real. If it was real, I would think that the pain would go away as I fully lost whatever it is that I am trying to hold on to, or it would get more and more unbearable as the loss became more and more irreversible.
For now, I will just enjoy those moments like the perverse pleasure that can be gained from becoming absorbed by unrequited love.