None. When you walk through that door it's an act of free will, and I will not have anything other than complete silence.

走过那道门,是你的自由，我不会做其他事,除非保持安静。

麻省理工公开课 - 固态化学导论课程节选

And although I don't really have the fantasy that many of you will read this stuff twice, if you had the time to do it, that would be a wonderful thing to do.

并且尽管我不会真的认为,你们中的有些人会读两遍这些材料，如果你有时间去读的话，那将会是很棒的事去做。

耶鲁公开课 - 死亡课程节选