can't judge a book by its cover

can't (or don't) judge a book by its cover

Meaning

• outward appearance cannot be an indicator of someone or something's value or worth
• you cannot know what someone or something is like just by looking the person or thing's appearance
• the quality or character of  someone or something cannot be judged just by looking at them
• an opinion of someone or something cannot be formed solely by seeing what's on the surface

Example Sentences

1. The candidate did not look very intelligent, but you can't judge a book by its cover.
2. The hotel looked attractive from outside, but the rooms were damp and not well maintained. You can't judge a book by its cover!
3. Do not form opinions of a persons character by looking at his appearance. You can't judge a book by its cover.
4. At first we did not want to go into the restaurant as it looked small and cramped; but the food was delicious – we realized that you can't judge a book by its cover.
5. The car was small and looked unsuited for a long trip, but packed a lot of power and was very solid. You can't judge a book by its cover.
6. That man may look very small and insignificant, but don't judge a book by its cover – he's a very powerful man in his circle.

Origin

This phrase has been in use since the mid 1800s.