The Rest of What Lord Acton Said
His over-quoted but ever-true dictum about "power corrupting" is not usually read in the context of what precedes it. Interesting.

“I cannot accept, your canon that we are to judge pope and king unlike other men, with a favorable presumption that they do no wrong. If there is any presumption, it is the other way against holders of power…
Power tends to corrupt, and absolute power corrupts absolutely”