As I have intimated, our scientific conclusions cannot be so important or so extensive as our logical conclusions, because they relate to a system of knowledge scarcely yet instituted: yet it is necessary to follow up the logical summary with a sketch of the proper nature and connection of the abstract studies that we have examined in succession; our present view regarding them as so many necessary elements of a single body of doctrine, according to our principle.

We have perceived throughout that, in the case of the human evolution at least, there exists a natural agreement between our knowledge and our needs. The knowledge which, is inaccessible to us is precisely that which could answer no purpose but gratifying a vain curiosity. We have no concern with anything but the laws of phenomena which affect human beings; such action, however indirect, constituting a basis of positive estimate, the full realization of which can follow only very remotely the manifestation of the corresponding needs, at any rate till we can institute a better research. This scheme must comprehend, on the one hand, Humanity itself, in its existence and action; and, on the other hand, the general medium, whose permanent influence is an essential element in the whole movement. Every scientific, as well as logical consideration, shows the necessity of the study of the medium; and thus naturally divides science into the two departments,—inorganic and organic science; the first being the indispensable preparation for the second; and the second simply modifying the phenomena of the first by a nobler action.