don't judge a book by its cover

What it means

Don't form an opinion about someone or something based only on outward appearance, because the reality may be quite different. It's a reminder to look beyond first impressions before deciding.

Examples

• The shabby little café had amazing food — don't judge a book by its cover.
• He seemed unfriendly at first, but don't judge a book by its cover.
• The car looked old, yet it ran perfectly; don't judge a book by its cover.
• She's quiet, but don't judge a book by its cover — she's brilliant.

Where it comes from

A 20th-century proverb, popularised in mid-century American usage, drawing on the obvious idea that a book's plain or fancy cover need not reflect its contents.

Related idioms