Foxes, when they cannot reach the grapes, say they are not ripe.

Understand the thought

Meaning in plain English

People may dismiss something they cannot obtain to make disappointment easier to bear. Check whether the criticism reflects the thing itself or a response to being denied it.

What the words are saying

The fox cannot reach the grapes and then describes them as unripe. The sequence makes the explanation suspect: the negative judgement arrives after the failed attempt to get what was wanted. Figuratively, a person may downgrade an opportunity or possession once it becomes unavailable, protecting pride by saying it was never desirable. The saying does not prove that every disappointed person’s criticism is false. A closer look may reveal genuine shortcomings. Compare the reasons offered before and after the refusal, and ask whether there is independent support for the changed judgement rather than treating disappointment as either proof or disproof.

Everyday example

A reader praises a fully booked workshop, then calls it worthless after failing to get a place; a friend asks whether anything about the workshop actually changed.

When to use it

Use it when a newly negative judgement closely follows failure to obtain something previously wanted.

Agent-assisted editorial interpretation. This explains the words; it does not by itself verify their author or earliest origin.