Not content with showing to chemists the “scientific type” towards which their science should tend, Comte suggests a contrivance in method which will bring them nearer to it. It is in no way like the hypothesis of affinities, for this appears to him to be even more “ontological” than the hypothesis of imaginary fluids or ethers. As always happens when we are concerned with metaphysical conceptions, the explanations which we draw from affinities consist in the reproduction in abstract terms of the very statement of the phenomenon.[147] To this hypothesis, which is not a scientific one since it bears up the mode of production of facts, Comte substitutes what he calls the “dualist hypothesis.” We ignore, he says, and it is not for us to seek the real manner in which the elements of which bodies are composed come to be grouped together. But, consequently, it is lawful for us, in the very circumscribed sphere of our positive research, to conceive the immediate composition of any substance whatever as merely _binary_, each of the two bodies so separated being able, according as the case may be, to lend itself to a similar analysis, equally binary, and so on, as the occasion arises. We do not affirm that dualism is a real law of nature. It will be a fundamental contrivance in chemistry, like the hypothesis of inertia in mechanics, and that of atoms in physics. It will serve to “simplify our elementary conceptions” in chemistry, and in having recourse to it we do not exceed “the special kind of liberty” of which our intellect may avail itself, in the institution of science.[148] The use of this hypothesis would allow us to endow chemistry with a “fine” character of unity and rationality which it lacks to-day. It is true that Comte himself confessed that this hypothesis, proposed by him in 1838, had yet “produced nothing” in 1851. But he explains this sterility to himself by the metaphysical spirit, from which chemists are not sufficiently freed. IV. We can now take in at a single glance the relations of the sciences of the inorganic world (including astronomy), with the totality of positive philosophy.[149] In several ways these sciences have contributed to the progress of the positive spirit. By their constitution, they allowed and prepared the formation of the more complex sciences of Biology and of Sociology. Moreover, their development struck a mortal blow at theological and metaphysical philosophy. Through them minds became familiarised with the idea of natural law. This idea was not so clearly brought to light by mathematics on account of their almost purely abstract character, and of the imperceptible part played in them by observation. It appears, on the contrary, as the mainspring of astronomy, of physics, and of chemistry. The whole effort of these sciences tends to discover invariable relations between phenomena given in experience.