You can't judge a book by its cover. This is a famous saying, but the latter is seldom used.

Let's first understand the definition of famous sayings: there are two definitions of famous sayings, namely famous sayings or famous sayings, which are generally meaningful and reveal certain truth to people. Famous sayings are the essence of one's wit, the wise statements made by all people, which require positive content, the wisdom of smart people and the experience of the elderly, and can be used as a concise statement of people's behavior norms.

So these two sentences are famous sayings.