We were not only innocent a half century ago with the innocency of irresponsibility; but we had a religious version of our national destiny which interpreted the meaning of our nationhood as God’s effort to make a new beginning in the history of mankind. Now we are immersed in world-wide responsibilities; and our weakness has grown into strength. Our culture knows little of the use and the abuse of power; but we have to use power in global terms. Our idealists are divided between those who would renounce the responsibilities of power for the sake of preserving the purity of our soul and those who are ready to cover every ambiguity of good and evil in out actions by the frantic insistence that any measure taken in a good cause must be unequivocally virtuous. We take, and must continue to take, morally hazardous actions to preserve our civilization. We must exercise our power. But we ought neither to believe that a nation is capable of perfect disinterestedness in its exercise, nor become complacent about particular degrees of interest and passion which corrupt the justice by which the exercise of power is legitimatized. Communism is a vivid object lesson in the monstrous consequences of moral complacency about the relation of dubious means to supposedly good ends.

–Reinhold Niebuhr, The Irony of American History ch. 1, pp. 4-5 (1952)