Interpretation: The price of all commodities is determined by the ratio of the quantity of commodities to the quantity of money. When the quantity of commodities or currencies changes greatly, the prices of all commodities will fluctuate up and down. In other words, the volume of goods increases and the price decreases; With the increase of money, the price is soaring. On the contrary, the quantity of goods is reduced and the price is expensive; Money decreases and prices fall. This is the first point. However, when the commodity is expensive, people see that the enterprises that operate this commodity have unique profits, so they flock to invest in this kind of enterprise, and the competition between sellers begins. Since there are more sellers, the number of people who need this commodity in society will not increase, and its price will definitely fall. On the other hand, because of the price drop, operators have to change their business one after another, so there are few sellers and the demand of society remains unchanged. So demand exceeds supply, and its price will rise.