忧虑是一种积极的心理活动，可以开阔人的思路。如果能正确引导这一情绪，你就可以洞察任何形势下的负面风险，并采取行动规避这些风险。
书籍是最安静且最恒久的朋友。
The true spirit of delight, the exaltation, the sense of being more than Man, which is the touchstone of the highest excellence, is to be found in mathematics as surely as in poetry.
如果某人试图说服你，想让你认为那不是传销，那么它就是传销。