To understand the present, we must dig into the past.

"Think wrongly, if you please, but in all cases, think for yourself."

I went to the woods because I wished to live deliberately. I wanted to live deep and suck out all the marrow of life, to put to rout all that was not life.

心理学的方法必须严格控制。

大兵之间只有一种区别，就是活大兵与死大兵之别。