… is from page 651 of the 1988 collection of Lord Acton’s writings and notes to himself (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:
You may govern by force, but you cannot at the same time hold by both physical and moral means.
DBx: Indeed so.
The greater is the amount of physical coercion that the state must credibly threaten to use against its citizens in order to pursue its goals, the more immoral are those goals.
