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The beauty of instrumental variables is that they allow us to see the world in a new light.
The greatest obstacle to being heroic is the doubt whether one may not be going to prove one's self a fool; the truest heroism is to resist the doubt; and the profoundest wisdom, to know when it ought to be resisted, and when to be obeyed.
Mental processes are nature's way of solving life's problems.
理论的任务不仅是了解自然是什么以及它是如何运作的,而且要尽可能接近理解为什么自然是这样的而不是其他样子的不可达到的目标。
作家在自己的国家必须是个陌生人。