Because you don't know how much more time you've got-- You can make a guess based on statistics, but as we saw, there's wild unpredictability.

因为你不知道你剩下多少时间-,你可以根据数据进行猜测，但是我们都知道，不可预见性太难把握。

耶鲁公开课 - 死亡课程节选

And at the same time it's rigorous, based on research.

同时又是严格的，以研究为基础。

哈佛公开课 - 幸福课课程节选