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. They will separate themselves out; they will go to enrich the stock of human ideas; they will add something to the truth which he himself mistakenly took as final; they will serve to explain the root of the error; for error itself is generally a truth misconceived, and it is only when it is explained that it is finally and satisfactorily confuted. Or, in the alternative, no element of truth will appear. In that case the more fully the error is understood, the more patiently it is followed up in all the windings of its implications and consequences, the more thoroughly will it refute itself. The cancerous growth cannot be extirpated by the knife. The root is always left, and it is only the evolution of the self-protecting anti-toxin that works the final cure. Exactly parallel is the logic of truth. The more the truth is developed in all its implications, the greater is the opportunity of detecting any element of error that it may contain; and, conversely, if no error appears, the more completely does it establish itself as the whole truth and nothing but the truth. Liberalism applies the wisdom of Gamaliel in no spirit of indifference, but in the full conviction of the potency of truth. If this thing be of man, _i. e._ if it is not rooted in actual verity, it will come to nought. If it be of God, let us take care that we be not found fighting against God.