… is from page 418 of Thomas Babington Macaulay’s magisterial The History of England  (1848-61), abridged edition, Hugh Trevor-Roper, editor (New York: Penguin Books, 1968):
We daily see men do for their party, for their sect, for their country, for their favourite schemes of political and social reform, what they would not do to enrich or to avenge themselves. At a temptation directly addressed to our private cupidity or to our private animosity, whatever virtue we have takes the alarm. But virtue itself may contribute to the fall of him who imagines that it is in his power, by violating some general rule of morality, to confer an important benefit on a church, on a commonwealth, on mankind. He silences the remonstrances of conscience, and hardens his heart against the most touching spectacles of misery, by repeating to himself that his interventions are pure, that his objects are noble, that he is doing a little evil for the sake of a great good. By degrees he comes altogether to forget the turpitude of the means in the excellence of the end, and at length perpetrates without one internal twinge acts which would shock a buccaneer.