A starving fox saw bunches of grapes hanging high in a tree. He tried to reach them and failed. Rather than admit the grapes were beyond him, he walked away insisting they were unripe anyway.
The grapes did not change. Only the fox’s description of them did.
Source: Aesop, “The Fox and the Bunch of Grapes,” The Complete Fables, fable 32, PDF p. 62. Retold.
What it argues
We often protect our self-image by downgrading what we failed to obtain. The rationalization removes the sting of failure, but it also prevents honest learning.
Use it for: motivated reasoning, rejection, envy, and post-hoc justification.