=Popular Rule through Public Opinion.=—We hear a good deal nowadays about public opinion. What is it? How is it ascertained? How does it make itself felt? In general, public opinion is the term which we apply to the predominating sentiment among the people. Public opinion is the sum-total of opinions held by individuals. It is not merely the snap-judgment of the majority, however, because _intensity_ of belief is a factor which counts in determining it. Public opinion is a composite of numbers and intensity. A majority of the people may hold a certain belief upon any public question; but if they hold it lightly, without attaching much importance to it, we do not speak of their sentiment as public opinion. It is only when sentiment attains the earnestness of conviction that the term public opinion can be properly applied to it. [Sidenote: The channels through which it makes itself felt.] Public opinion, in this sense, is continually exerting pressure upon all branches of government in the United States. It finds expression through the editorial columns of newspapers, through resolutions adopted by societies and organizations, through letters from voters to their representatives in Congress and in the legislatures, and through the conversation of people wherever they are gathered together. The representatives of the people are ever on the alert to discern the drift of public opinion.[24] They desire to keep in touch with it. A capable representative always keeps his hand upon the public pulse. When public opinion undergoes a change, the attitude of the government swings with it, slowly perhaps, but inevitably. Public opinion is not easy to ascertain exactly, for it cannot be measured by any process of arithmetic. Some men are better at gauging it than others. One of the attributes of a successful politician is his ability to estimate public opinion accurately. When we say, therefore, that we have “government by public opinion”, we mean that those who are in authority are influenced and guided by it. [Sidenote: Government by representatives.]