“Everyone is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”
As Quote Investigator explains, allegories about animals doing impossible things have been incredibly popular in the past century. But no, this one isn't from Einstein. (Source: http://quoteinvestigator.com/2013/04/06/fish-climb/.)
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Variant: Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.
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Albert Einstein 702
German-born physicist and founder of the theory of relativi… 1879–1955Related quotes

“The difference between genius and stupidity is that genius has its limits. ”

“Genius may have its limitations, but stupidity is not thus handicapped.”

“When there is a big tree small ones climb on its back to reach the sun.”
Source: No Longer at Ease (1960), Chapter 10 (p. 95)

“Intelligence is the ability of a species to live in harmony with its environment.”
Worldfest video http://www.youtube.com/watch?v=PnhqmF-RBu4

Its okay to tell a lie but believing in your own lies makes you the first victim, you become your own enemy which limits ability to think progressively towards success in life.
Quoted from his first book https://en.wikipedia.org/wiki/Success_and_Failure_Based_on_Reason_and_Reality, "Success and Failure Based on Reason and Reality" https://www.amazon.co.uk/SUCCESS-FAILURE-BASED-REASON-REALITY/dp/9970983903/ on Amazon, P.124 (July 2018)