… is from page 588 of the 1988 collection of Lord Acton’s writings (edited by the late J. Rufus Fears), Essays in Religion, Politics, and Morality; specifically, it’s a note drawn from Acton’s extensive papers at Cambridge University; (I can find no date for this passage):
America: At first they strove to preserve the rights of Englishmen. This failed, and they declared their rights as human beings. This had never been done so largely.
