It will be felt, I think, that the principal difficulty of the Positive Synthesis was met by my discovery of the laws of development, if we bear in mind that while that theory completes and co-ordinates the objective basis of the system, it at the same time holds it in subordination to the subjective principle. It is under the influence of this moral principle that the whole philosophical construction should be carried on. The inquiry into the Order of the Universe is an indispensable task, and it comes necessarily within the province of the intellect; but the intellect is too apt to aim in its pride at something beyond its proper function, which consists in unremitting service of the social sympathies. It would willingly escape from all control and follow its own bent towards speculative digressions; a tendency which is at present favoured by the undisciplined habits of thought naturally due to the first rise of Positivism in its special departments. The influence of the moral principle is necessary to recall it to its true function; since if its investigations were allowed to assume an absolute character, and to recognize no limit, we should only be repeating in a scientific form many of the worst results of theological and metaphysical belief. The Universe is to be studied not for its own sake, but for the sake of Man or rather of Humanity. To study it in any other spirit would not only be immoral, but also highly irrational. For, as statements of pure objective truth, our scientific theories can never be really satisfactory. They can only satisfy us from the subjective point of view; that is, by limiting themselves to the treatment of such questions as have some direct or indirect influence over human life. It is for social feeling to determine these limits; outside which our knowledge will always remain imperfect as well as useless, and this even in the case of the simplest phenomena; as astronomy testifies. Were the influence of social feeling to be slackened, the Positive spirit would soon fall back to the subjects which were preferred during the period of its infancy; subjects the most remote from human interest, and therefore also the easiest. While its probationary period lasted, it was natural to investigate all accessible problems without distinction; and this was often justified by the logical value of many problems that, scientifically speaking, were useless. But now that the Positive method has been sufficiently developed to be applied exclusively to the purpose for which it was intended, there is no use whatever in prolonging the period of probation by these idle exercises. Indeed the want of purpose and discipline in our researches is rapidly assuming a retrograde character. Its tendency is to undo the chief results obtained by the spirit of detail during the time when that spirit was really essential to progress.