忧虑是人们生存的重要条件。与忧虑的正面交锋可以为我们驱赶厌倦感，使我们的感觉更加敏锐，并且保持人类生存所必须的压力。
Anxiety is essential to the human condition. The confrontation with anxiety can relieve us from boredom, sharpen the sensitivity and assure the presence of tension that is necessary to preserve human existence.
The power of causal reasoning is that it allows us to predict the effects of actions we have never taken.
如果在战争获胜后得不到任何东西，不要开战。
A proof tells us where to concentrate our doubts.