The duty of man is the same in respect to his own nature as in respect to the nature of all other things.
The only thing you sometimes have control over is perspective. You don't have control over your situation. But you have a choice about how you view it.
The only thing that separates successful people from the ones who aren’t is the willingness to work really hard and to be really brave.
以客观角度来看，这个世界确实变得更好，但同时也变得更糟。前进一步，又倒退一步，仿佛宇宙在科技进步和文化倒退间达成平衡，使人类的进展呈钟形曲线。