Explaining "Walls have ears"

What does it mean?

The phrase "walls have ears" means that one should be cautious about what they say because unseen listeners could be present, implying that secrets or confidential information might be overheard.

Tone

Origin

The saying likely originates from a story about Dionysius of Syracuse (430–367 B.C.), who had a cave shaped like an ear carved into his palace to eavesdrop on conversations from other rooms. Over the centuries, similar listening structures were installed in various palaces, such as the Louvre in Paris. It was first recorded in English in its current form in 1620.