# it takes one to know one

idiom · CEFR B1

Source: https://englishreference.com/idiom/it-takes-one-to-know-one
Updated: 2026-08-10

## Meaning

Expressing the same underlying character-judgment themes as pot calling the kettle black or set a thief to catch a thief.

## Examples

- He called me lazy, but it takes one to know one.
- When my friend accused me of being stubborn, I laughed and said it takes one to know one.
- She dismissed his criticism of her dishonesty, retorting that it takes one to know one in such matters of character.

## Origin

20th-century retort; descends from the older proverb 'it takes a thief to catch a thief' (17th century). (disputed)

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.