I had a profoundly difficult trip that affected me deeply. It felt eternal, and when I emerged, I could feel it in my head like some antimemetic parasite that fed off disgust and terror. I can still remember the feeling, twenty years later, if I try, so I don't. I had to learn how not to be influenced by it, and in doing so, learned about myself. And as I changed, because I was aware of what I knew, I knew when I'd changed.

Our selves are not immutable, steady states. Our experiences shape us. It's a lesson learned to guard that carefully and jealously.