At least from my modern perspective, much of what Sun Tzu wrote in the art of war seems to border the line between common sense and painfully obvious.

However, if I were some Chinese military leader reading the art of war shortly after it was written and saw "So in war, the way is to avoid what is strong, and strike at what is weak." Or "There is no instance of a nation benefitting from prolonged warfare." Would I think to myself "Holy sh*t this Sun Tzu guy is a genius!" Or more along the lines of "Yeah I knew that why did you feel the need to write it down?".