In this way two great connected facts which occupy a considerable place in the philosophical history of our century are explained. We understand: 1. that the fate of metaphysics appears to be closely bound up with that of psychology, of ethics of the philosophy of history and of the moral sciences in general, while the connection between physics, for instance and metaphysics seems to be very weak; 2. that the foundation of sociology determines that of positive philosophy. So long as psychology speculates upon the nature of the soul and upon the laws of thought; ethics, upon the final cause of man, the philosophy of history, upon the final cause of humanity; metaphysics remains standing. Indeed it seems better able than positive knowledge to lead the human mind to a conception of the whole of the real. It appears to be all the more appropriate for doing this in that the point of view of the Absolute can be easily made to harmonise with the point of view of the Universal, in the same way as the conception of substance, whatever it may be, leads without any difficulty to the conception of the unity of substance. But, from the day when we no longer should seek anything but the laws of psychical, moral and social facts, refraining from any hypothesis as to causes and essences, (a method already made use of for all the other categories of phenomena), three results would be obtained at a single blow: metaphysical philosophy would disappear, social science would be created, and positive philosophy would be founded. According to the essential law of social dynamics, the metaphysical stage is never anything but a transitory one between the theological and the positive stages. The human intellect could not pass immediately from the former to the latter. The metaphysical stage which can assume an endless number of forms and of degrees, insensibly leads it from one to the other. Metaphysical philosophy partakes of the theological in so far as it claims to “explain” the totality of the Real by means of a first principle, and of the positive, in so far as it endeavours to demonstrate its “explanations,” and to bring them into accordance with the real knowledge already acquired. It originates in theology and it ends in science. But, however near it may come to positive knowledge, its original theological brand is never effaced. Were they compelled to choose between the theological and the positive doctrines, metaphysicians would certainly adopt the former. The essence of metaphysical philosophy is to tend towards the absolute, whilst positive philosophy only seeks the relative. In favouring the progress of positive science, metaphysical philosophy was working to make itself useless.