In an ideal world, where you can borrow and lend freely, an individual could choose consumption along any point on this line.

在理想情况下,你可以随意借贷,每个人都可以将这条线上任意一点,作为自己的消费额

耶鲁公开课 - 金融市场课程节选

Of course, you can take a function and take derivatives any number of times.

当然,你可以随意拿一个函数,对它求任意阶的导数

耶鲁公开课 - 基础物理课程节选