There was a graduate student in my cohort, this guy I dated, who told me he came to realize that doing physics is like this: there’s a concrete wall twenty feet thick, and you’re on one side, and on the other side is everything worth knowing. And all you have is a spoon. So you just have to take a spoon and start scraping at the wall: no other way. He works in a bookstore now.But I think of it this way. There is a jigsaw puzzle. It’s infinitely large, with no edges or corners to help you out. We have to put it together: it’s our duty. We will never finish, but we have to find our satisfactions where we can: when we place two pieces together that suggest we may have found the place where the sky touches the sea, or when we discover a piece that is beautiful in and of itself, that has an unusual color or a glimpse of an unexpected pattern. And the pieces that do not join together also tell you something. If there are very few eureka moments, then at least there are a thousand little failures, that point the way toward a hundred little joys.