you can't judge a book by its cover
Meaning
You shouldn’t form an opinion about someone or something based only on appearance or first impressions.
Origin
From the literal idea that a book’s cover doesn’t reveal the quality of its contents; popularized in 20th-century American English and reinforced by the 1946 song title “You Can’t Judge a Book by the Cover.”
Notes
Advisory, mildly cautionary tone. Implies appearances can be misleading. Used in casual or formal speech to discourage snap judgments; can sound preachy if overused.
Examples
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He looked intimidating, but he was incredibly kind—you can't judge a book by its cover.
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The restaurant seems plain from the outside, but the food is amazing; you can't judge a book by its cover.
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I thought that old laptop was useless, yet it still runs perfectly—you can't judge a book by its cover.
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She sounded quiet in meetings, but her ideas were the strongest; you can't judge a book by its cover.
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Don't dismiss that candidate because they're nervous today—you can't judge a book by its cover.
Grammar & Usage Notes
Usually fixed as “You can’t judge a book by its cover.” Variants: “Don’t judge a book by its cover.” Can be generalized: “You can’t judge X by its Y.”
Synonyms
- appearances can be deceiving
- don't judge by appearances
- looks can be deceiving
Antonyms
- take something at face value