possible, and which in some particular instances actually happens);[11] the universality of binary composition would have been a successful example of an hypothesis in anticipation of a positive theory, to give a direction to inquiry which might end in its being either proved or abandoned. But M. Comte evidently thought that even though it should never be proved--however many cases of chemical composition might always remain in which the theory was still as hypothetical as at first--so long as it was not actually disproved (which it is scarcely in the nature of the case that it should ever be) it would deserve to be retained, for its mere convenience in bringing a large body of phaenomena under a general conception. In a _resume_ of the general principles of the positive method at the end of the work, he claims, in express terms, an unlimited license of adopting "without any vain scruple" hypothetical conceptions of this sort; "in order to satisfy, within proper limits, our just mental inclinations, which always turn, with an instinctive predilection, towards simplicity, continuity, and generality of conceptions, while always respecting the reality of external laws in so far as accessible to us" (vi. 639). "The most philosophic point of view leads us to conceive the study of natural laws as destined to represent the external world so as to give as much satisfaction to the essential inclinations of our intelligence, as is consistent with the degree of exactitude commanded by the aggregate of our practical wants" (vi. 642). Among these "essential inclinations" he includes not only our "instinctive predilection for order and harmony," which makes us relish any conception, even fictitious, that helps to reduce phaenomena to system; but even our feelings of taste, "les convenances purement esthetiques," which, he says, have a legitimate part in the employment of the "genre de liberte" reste facultatif pour notre intelligence." After the due satisfaction of our "most eminent mental inclinations," there will still remain "a considerable margin of indeterminateness, which should be made use of to give a direct gratification to our _besoin_ of ideality, by embellishing our scientific thoughts, without injury to their essential reality" (vi. 647). In consistency with all this, M. Comte warns thinkers against too severe a scrutiny of the exact truth of scientific laws, and stamps with "severe reprobation" those who break down "by too minute an investigation" generalizations already made, without being able to substitute others (vi. 639): as in the case of Lavoisier's general theory of chemistry, which would have made that science more satisfactory than at present to "the instinctive inclinations of our intelligence" if it had turned out true, but unhappily it did not. These mental dispositions in M. Comte account for his not having found or sought a logical criterion of proof; but they are scarcely consistent