The main thing is to keep the main thing the main thing.

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

出自先秦《荀子·修身》。批评我而又批评得恰当的，他便是我的老师；肯定我而又实事求是的，他便是我的朋友；讨好奉承我的，他便是我的仇人。说明修身养性要有闻过则喜的雅量，要亲近正人君子而远离谄谀小人。这样，才会有利于自己道德的修炼进步。

"The study of computational complexity teaches us that some problems are inherently difficult, no matter how clever our algorithms are."

It always seems impossible until it's done.