Scientists can observe what they believe to be dark matter only through its gravity.

VOA: special.2009.07.21

Now, I've been saying kind things about Western civilization, but I would not want to deny that there is a dark side to the western experience and its way of life.

我刚刚一直说的都是西方文明光辉的一面,但我是不得不承认,西方文明,也有它黑暗的一面

耶鲁公开课 - 古希腊历史简介课程节选

Now, I've been saying kind things about Western civilization, but I would not want to deny that there is a dark side to the western experience and its way of life.

我刚刚一直说的都是西方文明光辉的一面,但我是不得不承认,西方文明,也有它黑暗的一面

耶鲁公开课 - 古希腊历史简介课程节选