Market participants' understanding of the monetization of a commodity at a certain moment, the core of the price is "human knowledge", and people are fundamental, and new transaction prices will occur between people; So what affects people's behavior? All transactions in the market are profit-seeking. Only when the market gives traders the expectation of rising will traders have the motivation to buy. Driven by constant expectations, more and more traders will participate, leading to price increases (as well as price declines); In the whole process of price movement, people's expectation of price determines the individual's buying and selling behavior, and finally produces new prices. When the psychological expectations of most people in the market are consistent, a resultant force of buying or selling is formed, which leads to the price rising or falling. Market psychological expectation is the direct cause of price rise and fall. Without psychological expectation, there will be no further trading behavior in the market, and there will be no price change. In the story of "tulip bubble", it was the scarcity of tulips when they first entered the Dutch market, that is, the demand was in short supply, which gave people the expectation of preserving or even appreciating the value of tulips, which led to the subsequent national speculation and the continuous rise of prices; In the same way, it is precisely because of the fiery speculation that the supply of tulips exceeds demand, which gives people the expectation of future price decline and eventually leads to subsequent panic selling. In the story of soybean futures on the Chicago Board of Trade, it never rains in the main soybean producing areas, and the soybean output has not changed. However, just because it rains outside the exchange (not the main soybean producing area), it inexplicably gives traders on the exchange a psychological expectation that it will rain, and the soybean output will increase and the price will fall in the future, leading to the collective selling of soybeans, which in turn leads to a cliff-like decline in soybean prices that day. Whether in stock market, spot market or foreign exchange market, the change of psychological expectation is the fuse of price rise and fall. The more drastic the change, the more drastic the market price fluctuation, so why does the price rise and why does it fall? The answer is: people expect prices to rise or fall in the future, so they take buying or short selling operations, leading to price rises or falls; The natural law of price rise and fall is actually determined by the psychological expectations of many traders. The influence of supply and demand on the market directly affects psychological expectation. In other words, we often say that supply exceeds demand or supply exceeds demand is not the direct cause of the rise and fall of market prices, but the relationship between supply and demand in the market acts on traders' emotions, and ultimately affects market prices by affecting the psychological expectations of traders in the market. Compared with the market with bookmakers such as stocks, the foreign exchange market is relatively pure, and there is no absolute banker, so traders can calmly follow the psychological expectations of the market.