Well no, because if you think about it, if Oz makes two spears and Adam make two axes, and then they trade, then they will each have saved an hour of work.
但不应该这样，假如你想想看， 如果奥兹制作2个矛，而亚当制作2个斧头， 然后他们交换做贸易， 他们每一个都节约了1小时工时。