it takes one to know one

English

Proverb

it takes one to know one

1. (colloquial) Assertion that an insult that was made by the party to whom the phrase is directed is also true of that party.
   • 1949, Nial Kent, The Divided Path, p. 358:

     There's an unkind saying that it takes one to know one, and it's almost true.

   • 1947, Poet Lore‎, p. 280:

     Anyone who appreciates Shakespeare as this author unquestionably does is another Shakespeare — it takes one to know one!

   • 1946, Gore Vidal, Williwaw‎, p. 45:

     “I’ve got a bad egg,” said Bervick. “I guess this was a pre-war egg.” […]

     “It takes one to know one,” said the Chief, referring back to the eggs.

See also

• I know you are but what am I

Usage notes

• Sometimes recited without the initial "it", which is implied.