But in addition to this foisting of the sciences upon philosophy by means of general similarities of history, the student will find that whatever inner deductive warrant is set forth is badly conceived in the appraisement of the original factors--Matter, Motion, and Force--terms to which no definite conceptions can be attached. And should any one be so rash as to attach to them such definite meanings as would render their logical use possible, then the deductive process which would have to be undertaken to render them into corollaries corresponding to concrete histories would very shortly bring him to confusion. Should he, again, confine himself to the definite chemical factors existent in the primordial nebulæ, then his deductive attempt would bring him to the impassable gulf at the commencement of life. And, moreover, should he import the factor of sentiency into some simple chemical aggregates, and should he be able to set forth some gradual development of mind in correlation with gradual changes of physical organism, then again in the absence of any knowledge as to the relations of the two he would find himself unable to work out the deductive process and fail in the system of _à priori_ explanations which philosophy requires. For philosophy, according to Mr. Spencer, demands a deductive process commencing with the apprehension of the relations subsisting between the factors of the universe at some particular stage, which deductive process shall be a counterpart of the actual histories of the universe. Such deductive explanations Mr. Spencer does attempt--mainly in the Biology--the most important as to results, and the most badly reasoned of all his works. It is attempted firstly in a very concrete manner, by a consideration of the properties of the chemical substances which form the bases of organisms, and of the properties of the surrounding agencies--light, heat, air, water, etc. To the inter-relation of these are applied the laws of mechanics, such as movement in the direction of least resistance, etc., and by their instrumentality at last are organisms supposed to be evolved which have, somehow, a concomitant of consciousness which is nevertheless not a factor in any action of an organism. In such a history however, it is found necessary to admit genesis, reproduction, and heredity, and these, since they cannot be explained, are accepted without explanation.