There are many ways, real and imaginary, of objectively verifying philosophic opinions. But they all reduce, we know, to trial by the law of contradiction. True, every one is aware that no single philosophic doctrine is able to support such a trial, so that, pending a better future, people consider it possible to display a certain tenderness in the examination. They are usually satisfied if they come to the conclusion that the philosopher made a genuine attempt to avoid contradictions. For instance, they forgive Spinoza his inconsistency because of his _amor intellectualis Dei_; Kant, for his love of morality and his praise of disinterestedness; Plato, for the originality and purity of his idealistic impulses; and Aristotle, for the vastyness and universality of his knowledge. So that, strictly speaking, we must confess that we have no real objective method of verifying a philosophical truth, and when we criticise other people's systems, we judge arbitrarily after all. If a philosopher suits us for some reason, we do not trouble him with the law of contradiction; if he does not, we summon him before the court to be judged with the utmost rigour of the law, confident beforehand that he will be found guilty on every count. But sometimes there arises the desire to verify one's own philosophic convictions. To play the farce of objective verification with them, to look for contradictions in oneself--I do not suppose that even Germans are capable of that. And yet one desires to know whether he does indeed possess the truth or whether he has only a universal error in his hands. What is to be done? I think there is a way. He should think to himself that it is absolutely impossible for his truth to be binding upon anybody. If in spite of this he still refuses to renounce her, if the truth can suffer such an ordeal and yet remain the same to him as she was before, then it may be supposed that she is worth something. For often we appreciate conviction, not because it has an intrinsic value, but because it commands a high price in the market. Robinson Crusoe probably had a totally different way of thinking to that of a modern writer or professor, whose books are exposed to the appreciation of his numerous confrères, who can create for him the renown of a wise man and a scholar, or utterly ruin his reputation. Even with the Greeks, whom we are accustomed to regard as model thinkers, opinions had--to use the language of economics--not so much a demand, as an exchange value.