In one ear and out the other

Origin

The simple, elegant imagery of information entering one ear and immediately exiting the other has been a universal observation about human attention for centuries. While echoes of this sentiment can be found in classical Latin, it firmly entered the English lexicon in the 16th century. The phrase was notably captured in John Heywood's influential 1546 collection, "A Dialogue Conteinyng the Nomber in Effect of All the Proverbes in the Englishe Tongue," where it appears as "In at the tone eare and out at the tother." This vivid metaphor perfectly illustrates the mental bypass, where words are heard but never truly processed, slipping away as quickly as they arrive.