Hindsight is 20/20
Meaning
It is easy to understand and judge past events perfectly after they have happened, but difficult to predict or act correctly beforehand.
Origin
The term "20/20 vision" itself comes from the Snellen eye chart, developed by Dutch ophthalmologist Hermann Snellen in the 1860s. It denotes normal visual acuity: a person standing 20 feet away can clearly see what a person with normal vision can see at 20 feet. By the mid-20th century, this medical measurement had seamlessly slipped into popular idiom. The phrase "hindsight is 20/20" began to emerge, transforming a literal measure of perfect sight into a metaphorical one. It captured the universal human experience of effortlessly seeing all the right moves and mistakes after the fact, turning the precision of vision into the perfect clarity of retrospective understanding.
Examples
- I should have known that stock would crash, but hindsight is 20/20.
- Looking back at all the red flags, it's clear she was going to leave him, but hindsight is 20/20.