If justice be the greatest good, as so generally asserted, then its negative, or injustice, must be the greatest evil. Hence error in men's opinions of what is justice will work that greatest evil. Society as a whole is liable to error in respect to justice; has often been mistaken in the past and may be mistaken today. The individuals composing society are seldom, if ever, wholly disinterested and dispassionate in their judgments. Each individual is prone to believe that what is apparently good for himself or his group or class, is in accord with justice. Himself persuaded that he is battling for justice, he does not see that he may be battling only for some advantage over others, for some individual relief from common burdens, for some privilege not to be accorded to others; does not see that what he is battling for may cause injustice to others. Through ignorance of the real nature of justice, the grant to one of his plea for what he calls justice may work grievous injustice to others. So when altruists, warm with sympathy, obtain the enactment of laws intended for the betterment of the less fortunate, they may at times do injustice to others and even to those they hoped to benefit. History records many instances where laws intended to insure justice had the contrary effect. Many a statute designed to prevent oppression has itself proved oppressive in operation. Many a theory of justice has been found to work injustice. A conspicuous and familiar instance is found in the history of the French Revolution. The Jacobins believed that their theories if given effect would usher in the reign of justice in France. They obtained power and exploited their theories only to bring in the Reign of Terror, that reign of terrible injustice. As mistakes and grievous mistakes have been made in the past as to what is justice, so they will be made now and in the future, and can be lessened only by greater wisdom and forethought, by greater effort to consider justice apart by itself, with philosophical detachment, with minds unclouded by pity, sympathy, charity, and other like virtues, on the one hand, or by envy, hate, prejudice, and like evil sentiments, on the other. True, men are more enlightened now and education is more general, but society is more complex, with more diverse and conflicting interests, than formerly. The social mechanism is now so intricate that even a slight disturbance in one part may disarrange the whole. Injustice to one may injure the many. Hence the duty of ascertaining as completely as possible the real nature of justice is as imperative today as ever. As declared by Ulpian, this duty is especially incumbent upon those who have to do with the framing or administration of the laws, since justice can be enforced only by law.