Who can afford to do professional work for nothing?

一切都是美好的，没有任何伤害。

The interplay between mathematics and physics has led to some of the most profound insights in science.

我一直都很幸运。机遇很少凭空出现。所以，当它们出现时，你一定要抓住。

出自汉·桓宽《盐铁论·险固》。这句话以“地利”与“人和”、“武力”与“文德”的对比，阐明了实行仁政对于治国安邦的重要性。