Suppose you know someone, a long time ago. You share things, drink deeply of each other. Then you drift apart, life takes you in different directions, the bonds are not strong enough. Or maybe you get torn apart by external circumstance. Years later, you meet that person again, in the same sleeve, and you go through it all over again. What's the attraction? Is this the same person? They probably have the same name, the same approximate physical appearance, but does that make them the same? And if not, does that make the things that have changed unimportant or peripheral? People change, but how much? As a child I'd believed there was an essential person, a sort of core personality around which the surface factors could evolve and change without damaging the integrity of who you were. Later, I started to see that this was an error of perception caused by the metaphors we were used to framing ourselves in. What we thought of as personality was no more than the passing shape of one of the waves in front of me. Or, slowing it down to more human speed, the shape of a sand dune. Form in response to stimulus. Wind, gravity, upbringing. Gene blueprinting. All subject to erosion and change. The only way to beat that was to go on stack forever.