生活的目的不是快乐。它是有用、可敬、富有同情心，让你活得有意义且活得好。

The secret of change is to focus all of your energy, not on fighting the old, but on building the new.

"Do not wait for leaders; do it alone, person to person."

The deeper you go into mathematics, the more you realize how interconnected everything is.

逻辑学研究不仅仅是关于形式系统，更是关于理解人类推理的本质。