To the _Letters_ De Maistre has prefixed a quotation, which is to the effect that all great men have been intolerant, and that it is right to be so. "Let him who comes across a well-intentioned sovereign," says Grimm, the Encyclopedist, "preach tolerance in matters of faith to him, so that he may fall into the snare, and, by his toleration, give the persecuted party time to recover and prepare itself, when its turn of power comes, to crush its opponent. Voltaire's discourse, with its babble of tolerance, is a discourse only for simpletons and those who allow themselves to be fooled, or for people who have no interest in the matter." A gross fallacy conceals itself in this argument. Every genuine, overpowering enthusiasm naturally makes tolerance impossible. Yet Voltaire's doctrine is none the less valid because of this. The difficulty is easy of solution. The principle of intolerance is the theoretical, that of tolerance the practical, principle. In theory no consideration, no toleration, no mercy! For error must be crushed and torn asunder, follies must be blown from the cannon's mouth, and lies flayed alive. But what about the liar, and the fool, and the erring one? Are they also to be hewn asunder, or flayed alive, or blown from the cannon's mouth? They are to go their way. The domain of real life is the domain of tolerance. De Maistre's _Examen de la philosophie de Bacon_ was not published until after its author's death. It is the most disputatious and tedious of his works, and one in which the combative champion of Christianity is plainly grappling with a subject that is beyond his powers. He desired to confute Bacon because he believed that the ungodliness of the French philosophy of the eighteenth century was entirely to be ascribed to his influence; and he falls upon him with positive theological fury, attacking all his theories--his theory of consciousness, of nature, of light, of the weather, of the soul, of religion; attacking him where he is right, and where, for once in a way, he is wrong; finding him out in immaterial and merely superficial inconsistencies; pointing out defects in his Latin and in his taste; fighting in a noisy, violent, dogmatic manner, with weapons drawn from the arsenals of supernaturalism and tradition. In single chapters, such as that on _Causes Finales_, he displays a certain futile acuteness; in others, such as that entitled _Union de la Religion et de la Science_, cold-blooded fanaticism. In this latter chapter we read: "Science undoubtedly has its value, but it is necessary that it should be kept within bounds.... It has been very aptly said that science resembles fire: confined to the hearths which are destined to receive it, it is man's most useful and powerful servant; left to the hazard of chance, it is a terrible scourge."