The beauty of mathematics is that it is both precise and creative.
The most important thing in communication is hearing what isn't said.
Challenges are opportunities in disguise; embrace them.
出自汉·桓宽《盐铁论·通有》。天下的利益，没有人不想得到，因此要能够得到山中和海里的货物，便会不会不富有。这句话指出应大力开采山中和海里的物质资源。