What do we signify by words like me, myself, and I? What does a story mean that starts with In my childhood? What is that strange possession you, which stays the same throughout your life? Are you the same person you were before you learned to read? You scarcely can imagine, now, how words looked then. Just try to look at these words without reading them:
We find it almost impossible to separate the appearances of things from what they've come to mean to us. But if we cannot recollect how things appeared to us before we learned to link new meanings to those things, what makes us think we can recollect how we ourselves appeared to us in previous times? What would you say if someone asked questions like these:
Are you the same person now that you once were, before you learned to talk? Of course I am. Why, who else could I be? Do you mean that you haven't changed at all? Of course not. I only mean I'm the same person — the same in some ways, different in others — but still the same me. But how can you be the same as the person you were before you had even learned to remember things? Can you even imagine what that was like? Perhaps I can't — yet still there must have been some continuity. Even if I can't remember it, I surely was that person, too.
We all experience that sense of changelessness in spite of change, not only for the past but also for the future, too! Consider how you are generous to future self at present self's expense. Today, you put some money in the bank in order that sometime later you can take it out. Whenever did that future self do anything so good for you? Is you the body of those memories whose meanings change only slowly? Is it the never-ending side effects of all your previous experience? Or is it just whichever of your agents change the least as time and life proceed?