Public opinion is a new compelling political force which has come into the world since the Middle Ages. In fact, it is a development of the last century; before the French Revolution nothing of the kind was known or dreamed of in Europe. This new force in political life may be divided into two types. One is the popular belief in the fitness or rightness of something, a belief that certain lines of conduct should be followed or a certain opinion held by good citizens or right-thinking persons. This is what Mr. Balfour calls “climate.” Such a belief does not impose any duty on anybody beyond outward conformity to the accepted standard. But public opinion in the true sense is a consensus among large bodies of persons which acts as a political force, imposing on those in authority certain enactments or certain lines of policy.