The teaching of Mill brings us close to the heart of Liberalism. We learn from him, in the first place, that liberty is no mere formula of law, or of the restriction of law. There may be a tyranny of custom, a tyranny of opinion, even a tyranny of circumstance, as real as any tyranny of government and more pervasive. Nor does liberty rest on the self-assertion of the individual. There is scope abundant for Liberalism and illiberalism in personal conduct. Nor is liberty opposed to discipline, to organization, to strenuous conviction as to what is true and just. Nor is it to be identified with tolerance of opposed opinions. The Liberal does not meet opinions which he conceives to be false with toleration, as though they did not matter. He meets them with justice, and exacts for them a fair hearing as though they mattered just as much as his own. He is always ready to put his own convictions to the proof, not because he doubts them, but because he believes in them. For, both as to that which he holds for true and as to that which he holds for false, he believes that one final test applies. Let error have free play, and one of two things will happen. Either as it develops, as its implications and consequences become clear, some elements of truth will appear within it.