Someone asked Einstein, "You are always unprecedented in the field of physics, so why bother to study tirelessly?" Why don't you rest comfortably? "Einstein didn't answer this question immediately, but found a pen and a piece of paper, drew a big circle and a small circle on the paper, and said to the young people," Under the present circumstances, maybe I know a little more about physics than you. As you know this small circle, I know this big circle, but the whole knowledge of physics is boundless. For a small circle, its circumference is small, that is, its contact surface with the unknown field is small, and he feels that he knows very little; The circumference of the circle in contact with the outside world makes me feel that I have more unknown things and will work harder to explore them. "