certain hypothetical principles. Metaphysical philosophy differs from theological, in its admission of the notion of constancy or invariableness in the movements of Nature; and from positive, in its hypothesis of an agency superadded to the phenomena—in its declining to confine itself to the observed fact, and its pertinacious suggestion of an explanation for the fact—in its imagining an entity inhering in substances as an invariable real presence. Thus, the metaphysical physiologist, for example, instead of contenting himself as the positivist does, with observations restricted to biological phenomena, with a view to apprehend the laws of their action, proceeds to speculate on the vital essence, on the causes of life, on the principle of existence,—pronouncing the subject of his research, "chemical affinity," or "electricity," or "nervous fluid," or what not. And again observe: no man who still affects even so abstract a phrase as "the Laws of Nature," has yet emerged from this second, or metaphysical, stage, into the positive third. For, Law is the subtle but super-subtle, the delicate but supposititious "abstract entity," which metaphysics gratuitously superadds to concrete fact, and which, as imaginary and potentially misleading, is nehushtan to the iconoclastic protestantism of positive science.
What, then, is the third phase—what is this positive philosophy, so revolutionary in its policy, so exterminating in its decrees?
It is that phase in the development of Humanity, social and individual, in which the mind, rejecting as futile all speculation about cause and principle and essence, limits its inquiry to phenomena, and to their unvarying relations, simply with a view to the mastery of their laws. Positive Philosophy is, therefore, defined to be, the Explanation of the Phenomena of the Universe. The Why it declines to scrutinise, as something far above out of its reach. The How it sedulously and solely investigates. "The positive stage," says Mr. Lewes, "explains phenomena by ascertained laws, laws based on distinct and indisputable certitude gathered in the long and toilsome investigation of centuries; and these laws are not only shown to be demonstrable to reason, but accordant wit fact; for the distinguishing characteristic of science is, that it sees and, foresees. Science is prevision. Certainty is its basis and its glory." In this "recognition of invariableness" lies the "germ of science," because on it alone can prevision of phenomena depend—prevision being the test of knowledge.
Now, all the sciences, physical and social—this is a capital characteristic of M. Comte's philosophy—all are to be regarded as branches of one Science, and so to be investigated on one and the same Method. The student must therefore arrange the sciences according to their dependence on each other; beginning with the "simplest (most general) phenomena, and proceeding successively to the most complex and particular." By which rule, the following will be the order in which he studies the five sciences involved in the positive method—for it is peremptorily enforced, as a fundamental condition to success in such study, that the sciences should be learned in this their natural order, to the infringement of which rule is ascribed the present incoherent aspect of scientific culture ("some sciences being in the positive, some in the supernatural, and some in the metaphysical stage," with minute self-contradictory subdivisions). First: the Mathematical sciences—since in them the ideas dealt with are
