The story of how money replaced barter is familiar to every schoolchild, but it is worth repetition for the light it throws on the nature of money.

• 对于货币如何替代易货贸易的故事，每个上学的孩子都很熟悉，不过在这里仍然值得重述一下，因为这个故事阐明了货币的性质。