Source: The origin of the modern variation is unknown. The earliest known printed reference to the actual phrase “Curiosity killed the cat” is in James Allan Mair’s 1873 compendium A handbook of proverbs: English, Scottish, Irish, American, Shakesperean, and scriptural; and family mottoes, where it is listed as an Irish proverb on page 34.

Note: The proverb has been wrongly attributed to Eugene O’Neill, who included the variation, “Curiosity killed a cat!” in his play Diff’rent from 1920.

Meaning: Used to warn of the dangers of unnecessary investigation or experimentation.