Monetary expression of commodities. It is an idea that commodities show their value through exchange with money after the emergence of money, that is, price is an abstract thing, not a specific amount of money. The price of a commodity depends on the value of the commodity itself on the one hand, and on the value of the currency itself on the other. The price will change if one of the two changes, or if they do not change in the same aspect and in the same proportion. In addition, the price will fluctuate around the value with the market supply and demand of commodities. But from the long-term trend, from the average point of view, or from the whole society, the price and value of goods are consistent, which is also the embodiment of the law of value.