在数学中，提出问题的艺术必须比解决问题更有价值。
In mathematics, the art of proposing a question must be held of higher value than solving it.
《与邹鲁的谈话》（1919年6月）
A man of genius makes no mistakes. His errors are volitional and are the portals of discovery.
可持续发展不仅仅是种树，而是在正确的地方为了正确的理由种植正确的树。