“Thermodynamics is a funny subject. The first time you go through it, you don't understand it at all. The second time you go through it, you think you understand it, except for one or two small points. The third time you go through it, you know you don't understand it, but by that time you are so used to it, it doesn't bother you anymore.” --- Arnold Sommerfeld
热力学是个蛮有搞头的学科。搞第一遍后，你根本不懂它。搞第二遍后，除了一两小处，你以了你懂了。搞三遍后，你知道你没有懂，但却已经习惯于此，它再也不会令你不安了。（阿诺.索末菲）