We had a similar, even higher price-to-earnings ratio of about forty-six at the peak in 2000 and it corrected way down.

000年时我们的市盈率甚至更高,达到了46,后来经过修正降低了

耶鲁公开课 - 金融市场课程节选

That is the whole triumph of calculus is to know that by looking at the position now, the position slightly later and taking the ratio and bringing later as close as possible to right now, we define a quantity that we can say is the velocity at this instant.

这就得靠微积分了,通过了解它现在的位置,和一小段时间以后的位置,计算它们的比,再让时间间隔尽可能缩短,我们就定义了一个,被我们称之为瞬时速度的物理量

耶鲁公开课 - 基础物理课程节选