См. Актоновы "Очерки становления свободы".
А вот знаменитая фраза в контексте:
"I cannot accept your canon that we are to judge Pope and King unlike other men, with a favourable presumption that they did no wrong. If there is any presumption it is the other way against holders of power, increasing as the power increases. Historic responsibility has to make up for the want of legal responsibility. 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. That is the point at which the negation of Catholicism and the negation of Liberalism meet and keep high festival, and the end learns to justify the means. You would hang a man of no position, like Ravaillac; but if what one hears it true, then Elizabeth asked the gaoler to murder Mary, and William III ordered his Scots minister to extirpate a clan. Here are the greater names coupled with great crimes. You would spare these criminals, for some mysterious reason. I would hang them higher than Haman, for reasons of quite obvious justice; still more, still higher, for the sake of historical science.
The inflexible integrity of the moral code is, to me, the secret of the authority, the dignity, the utility of history. If we may debase the currency for the sake of genius, or success, or rank, or reputation, we may debase it for the sake of a man's influence, of his religion, of his party, of the good cause which prospers by his credit and suffers by his disgrace. Then history ceases to be a science, an arbiter of controversy, a guide of the wanderer, the upholder of that moral standard which the powers of earth, and religion itself, tend constantly to depress."