可持续发展不是选择题，而是责任。

对天资在中等程度以上的人，可以和他谈论高深的学问；而对于中等以下天资的人，则不可以和他谈论高深的学问。

The existence of a legal system depends on the acceptance of secondary rules by officials.

Sometimes the hardest thing in life is to know which bridge to cross and which to burn.

Technology should serve the forest, not exploit it.《Sustainable by Design》