If history were taught in the form of stories, it would never be forgotten.

The labor which it would require to make a single one of these guns by hand would exhaust the patience and perseverance of any ordinary workman.

释义：从天下的角度看，应遵循天下的公理，天下不是某一姓的私有财产。

预测未来的最好方法就是创造未来。