The phrase “Power tends to corrupt, and absolute power corrupts absolutely” is most commonly attributed to Lord John Dalberg-Acton, 1st Baron Acton. He wrote it in a letter to Bishop Mandell Creighton in 1887, expressing the view that power can erode moral judgment and that unchecked or unlimited authority tends to lead to corruption. The exact wording appears in Acton’s correspondence and has since become a widely cited summary of concerns about power and morality.

If you’d like, I can share more about the context of Acton’s letter, how the quotation evolved in popular culture, and how historians assess its original form and attribution.