国际体系本质上是竞争性的，国家不断试图互相超越。

The complexity of a learning problem is often determined by the size and structure of the hypothesis space.

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 it be obeyed.

I think that God, in creating Man, somewhat overestimated his ability.