当某种观念的“传染率”升高到足以支撑泡沫的程度，泡沫便应运而生了，问题是这种传染率的高低取决于人们的思维模式，而后者是极难进行判断的。
A bubble forms when the contagion rate goes up for ideas that support a bubble. But contagion rates depend on patterns of thinking, which are difficult to judge.