If you knew only the third derivative of the function, you can have something quadratic in t without changing the outcome.

如果方程里有三阶导数,你就可以引入一个二次项,但是结果却不会变

耶鲁公开课 - 基础物理课程节选

Third,premise related to the first is opposed to happiness which is primarily function of external circumstances.

第三，这个前提与,与决定幸福的,外部环境无关。

哈佛公开课 - 幸福课课程节选