twenty-twenty hindsight

twenty-twenty hindsight idiom
Knowledge after the fact, as in With twenty-twenty hindsight, I wouldn't have bought these tickets. This idiom uses twenty-twenty in the optometrist's sense, that is, “indicating normal vision,” and hindsight in the sense of “looking back” or “reconsidering.” [First half of 1900s]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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