It's part of a quote that's generally rendered as: "Power corrupts; absolute power corrupts absolutely." It's from a letter written by Lord Acton to Bishop Cr

It's part of a quote that's generally rendered as: "Power corrupts; absolute power corrupts absolutely." It's from a letter written by Lord Acton to Bishop Creighton in 1885. A more complete quote is: "Power tends to corrupt, and absolute power corrupts absolutely. Great men are almost always bad men, even when they exercise influence and not authority, still more when you superadd the tendency or the certainty of corruption by authority. There is no worse heresy than that the office sanctifies the holder of it."