> This is a depressing thought to consider in (linear) middle age, but it is hard to escape the feeling that it is essentially true. Childhood memories have an intensity and a vibrancy that it is difficult for the rest of life to match.

This is just not my experience at all. I had a great childhood, but ask me about the most vibrant moments, and very few of them came before I was 18. The births of my children, my wedding, meeting my wife, lazy afternoons in college...