The problem of the organisation of beliefs would seem to come under two heads. In the first place we have the philosophical problem: how to establish a system of principles and beliefs capable of being universally admitted; and, in the second place, a social problem: how to bring all minds into the new faith. But this distinction only appears on the surface. As a matter of fact, the solution of the first problem will necessarily imply that of the second. Does not the principal cause for the lack of common discipline lie in the disorder which troubles the mind of each individual? If intellects are divided among themselves it is because each intellect is divided against itself. Let one of them succeed in establishing a perfect harmony within itself, and by the mere force of logic, this harmony, by gradual diffusion will be communicated to the others--once true philosophy is established, the rest will only be a matter of time. It will therefore suffice to examine the opinions and beliefs which actually exist in _one_ mind, and to inquire into the conditions necessary to substitute in it harmony to anarchy, or in a word, to realise within it a _perfect logical coherence_. As Descartes, in order to test all his knowledge, had only to examine the sources from which it originated, so Comte, in order to verify the logical compatibility of his opinions, will content himself with the consideration of the methods which have furnished him with them. If he discovers methods which mutually tend to exclude each other, he will have found the cause of the mental disorder which gives birth to all the evils we see troubling modern society. At the same time he will have discovered the remedy which will bring about the disappearance of those contradictions. The human mind is so constituted, that the first thing it requires is unity. Understanding is spontaneously systematic. Opinions merely in juxtaposition in the mind but logically irreconcilable cannot satisfy it. As a matter of fact, the contradiction, even when it is ignored, nevertheless impresses itself. Whether we know it or not, each of our opinions implies a complexus of connected opinions all arrived at by the same method as the one in question; and this complexus is itself part of the more considerable whole which finally completes itself in a comprehensive conception of the world given in experience.