From The Way of Zen by Alan Watts (which I find myself re-reading and re-reading for fuller comprehension):

We learn, very thoroughly though far less explicitly, to identify ourselves with an equally conventional view of “myself.” For the conventional “self” or “person” is composed mainly of a history consisting of selected memories, and beginning from the moment of parturition. According to convention, I am not simply what I am doing now. I am also what I have done, and my conventionally edited version of my past is made to seem almost more the real “me” than what I am at this moment. For what I am seems so fleeting and intangible, but what I was is fixed and final. It is the firm basis for predictions of what I will be in the future, and so it comes about that I am more closely identified with what no longer exists than with what actually is!

It is important to recognize that the memories and past events which make up a man’s historical identity are no more than a selection. From the actual infinitude of events and experiences some have been picked out—abstracted—as significant, and this significance has of course been determined by conventional standards.