When someone refuses to reveal the source of a juicy piece of information and says, “A little bird told me,” they’re drawing on an idea that is more than 2,000 years old.

One of its earliest known ancestors appears in the Bible. Ecclesiastes warns against saying something damaging about a king, even in the privacy of your own home:

“for a bird of the air shall carry the voice, and that which hath wings shall tell the matter.”

In other words, be careful what you say. Somehow, word gets around.

Birds had long been associated with messages, omens and secret knowledge in ancient cultures, so the idea of a bird carrying information continued to turn up in literature and folklore.

Jonathan Swift sometimes gets credit for inspiring the modern expression because he used similar bird-and-secret imagery in his writing. But the underlying idea was already ancient by Swift’s time.

The precise expression “a little bird told me” emerged much later in English as a teasing way of saying, “I know something, but I’m not revealing my source.”

When someone tells you that “a little bird” gave away your secret, that bird comes with a surprisingly long pedigree. More than two millennia ago, Ecclesiastes was already warning that even words spoken in private could somehow take flight.