世界上充满了显而易见的事情，但没有人会偶然观察到。
The world is full of obvious things which nobody by any chance ever observes.
Start by doing what's necessary; then do what's possible; and suddenly you are doing the impossible.
可持续性不仅仅是植树，而是在正确的地方种植正确的树木，并确保它们世代繁茂。
Mathematics is not about numbers, equations, computations, or algorithms: it is about understanding.
The night is a great book, but the stars are its letters.