物理定律必须以独立于坐标系选择的方式表述。
Your smarts will come in handy because you will travel in a land of marvels. We humans -- plodding as we are -- will astonish ourselves. We'll invent ways to generate clean energy and a lot of it. Atom by atom， we'll assemble tiny machines that will enter cell walls and make repairs. This month comes the extraordinary but also inevitable news that we've synthesized life. In the coming years， we'll not only synthesize it， but we'll engineer it to specifications. I believe you'll even see us understand the human brain. Jules Verne， Mark Twain， Galileo， Newton -- all the curious from the ages would have wanted to be alive most of all right now. As a civilization， we will have so many gifts， just as you as individuals have so many individual gifts as you sit before me.
If you think about something at three o'clock in the morning and then again at noon the next day, you get different answers...
译文：高看自己，事事就很难有长进；低看自己，事事就不能成功。赏析：不管何时，我们不能骄傲自大，目空一切，更不能自暴自弃，妄自菲薄，畏首畏尾。骄傲自满会让人失去理智，自轻自贱会让人失去自信，这两种极端的处事态度对我们的人生都是不利的。
数学不仅仅是关于数字、方程、计算或算法：它是关于理解的。