It wasn't until the 20th century, so almost 200 years later, that we learned how to do this.

在詹纳研制出天花疫苗二百多年后,直到二十世纪,我们才知道如何做到这一点

耶鲁公开课 - 生物医学工程探索课程节选

And he talked about this over 200 years ago; Aristotle over 2000 years ago.

他在二百多年前谈到快乐;,亚里斯多德在二千多年前也谈过。

哈佛公开课 - 幸福课课程节选