Conventions are one reason why the appetite to buy financial assets tends to feed on itself (see chart 2).In textbook markets for goods, price increases lead to a fall in demand and to substitution.

• 购买金融资产的欲望，往往能够依凭这种欲望本身不断加深（见图二）我们在教科书中学到的是，产品市场价格上涨，需求下降，替代品需求上升。