The defenders of the French Revolution professed to wish, with Robespierre, “that morality may be substituted for egotism [self-interest].” What did Robespierre mean by “morality” or “virtue”? How do Christian notions of morality and virtue compare with the definitions offered by Robespierre, and by his successor, Pierre Joseph Proudhon? And how do these revolutionary notions of “morality” and “virtue” help to explain the wildly different outcomes between the American Revolution and French Revolution, which seemingly started with such similar principles in their respective Declarations of Independence and of the Rights of Man and Citizen?