The best way to predict the future is to create it.

心灵的钟摆在意与非意之间摆动，而非对与错之间。

数学不知道种族或地理界限；对于数学来说，文化世界是一个国家。

Buying tools: Start by buying the absolute cheapest tools you can find. Upgrade the ones you use a lot. If you wind up using some tool for a job， buy the very best you can afford.