“Time speeds up as it goes by. Someone explained to me that there is a mathematical reason for this: as you age, each year becomes a smaller percentage of the life you have already lived. I’m forty-two as I write this. One year now represents a small percentage of my forty-two years (about 2.38 percent). But when I was eight, one year was a really long time; it was an eighth of my life. (This is why summer lasted about four years when you were a kid.) This may be why I now feel an urgency to know more, to do more, to be more.”