思考是最困难的工作,这也是为什么很少有人这么做。
Thought is the most difficult task, which is why so few engage in it.
江河的水之所以浩浩荡荡,并非只由一个源头流出来;无比珍贵的皮衣,并非只由一只狐狸腋下的毛皮所能制成。