We know what censorship is. Censorship is the banning of books that have been published and that have been deemed by the state authorities to be dangerous or harmful in some way.

我们知道什么是控制，控制就是,禁止已经出版的书籍和被政府认为,在某些方面非常危险和有害的。

耶鲁公开课 - 弥尔顿课程节选

And also, it's useful because harmful stimuli are noticed but when something has shown itself to be part of the environment you don't notice it anymore.

而且它还是非常有用的,因为危险刺激会吸引到你的注意,但当某物被视为环境的一部分时,你便不会再去注意到该物体。

耶鲁公开课 - 心理学导论课程节选