The quote, "Power tends to corrupt, and absolute power corrupts absolutely," is credited to Lord Acton, an English historian and moralist. He articulated this idea in an 1887 letter, emphasizing the tendency for those in power to become corrupt, especially when their power is unchecked. This quote reflects the profound concern about the concentration of authority without accountability and has been influential in discussions about governance, ethics, and the necessity of checks on leaders' power.