This fundamental doctrine of Positivism is not to be attributed in the full breadth of its meanings to any single thinker. It is the slow result of a vast process carried out in separate departments, which began with the first use of our intellectual powers, and which is only just completed in those who exhibit those powers in their highest form. During the long period of her infancy Humanity has been preparing this the most precious of her intellectual attainments, as the basis for the only system of life which is permanently adapted to our nature. The doctrine has to be demonstrated in all the more essential cases from observation only, except so far as we admit argument from analogy. Deductive argument is not admissible, except in such cases as are evidently compounded of others in which the proof given has been sufficient. Thus, for instance, we are authorized by sound logic to assert the existence of laws of weather; though most of these are still, and, perhaps, always will be, unknown. For it is clear that meteorological phenomena result from a combination of astronomical, physical and chemical influences, each of which has been proved to be subject to invariable laws. But in all phenomena which are not thus reducible, we must have recourse to inductive reasoning; for a principle which is the basis of all deduction cannot be itself deduced. Hence it is that the doctrine, being so entirely foreign as it is to our primitive mental state, requires such a long course of preparation. Without such preparation even the greatest thinkers could not anticipate it. It is true that in some cases metaphysical conceptions of a law have been formed before the proof really required had been furnished. But they were never of much service, except so far as they generalized in a more or less confused way the analogies naturally suggested by the laws which had actually been discovered in simpler phenomena. Besides, such assertions always remained very doubtful and very barren in result, until they were based upon some outline of a really Positive theory. Thus, in spite of the apparent potency of this metaphysical method, to which modern intellects are so addicted, the conception of an External Order is still extremely imperfect in many of the most cultivated minds, because they have not verified it sufficiently in the most intricate and important class of phenomena, the phenomena of society. I am not, of course, speaking of the few thinkers who accept my discovery of the principal laws of Sociology. Such uncertainty in a subject so closely related to all others, produces great confusion in men’s minds, and affects their perception of an invariable order, even in the simplest subjects. A proof of this is the utter delusion into which most geometricians of the present day have fallen with respect to what they call the Calculus of Chances; a conception which presupposes that the phenomena considered are not subject to law.