"matter, then, in its ultimate nature, is as absolutely incomprehensible as space and time." In the second part of the work, in chapters treating of "The Indestructibility of Matter," "The Continuity of Motion," and "The Persistence of Force," I have at some length elaborated the view that force is the ultimate component of thought into which our conceptions of external existences are resolvable. Summing up the first of these chapters, I have said, "Thus, then, by the indestructibility of matter, we really mean the indestructibility of the force with which matter affects us." At the close of the second of these chapters I have argued that "the continuity of motion, as well as the indestructibility of matter, is really known to us in terms of force;. . . that which defies suppression in thought, is really the force which the motion indicates." And then in the third chapter, having shown how the truths that matter is indestructible and motion continuous, can be known to us only as corollaries from the truth that force is persistent—that force is that "out of which our conceptions of matter and motion are built"—I have gone on to say that, "by the persistence of force, we really mean the persistence of some power which transcends our knowledge and conception." Throughout all which arguments the implication is that I hold matter and motion to be conditioned manifestations of this unknown power. Being aware of the perversity of critics, I have, in the "Summary and Conclusion," again endeavored to bar out misinterpretation. Here is one of the sentences it contains: "Over and over again it has been shown in various ways that the deepest truths we can reach are simply statements of the widest uniformities in our experience of the relations of matter, motion, and force; and that matter, motion, and force are but symbols of the unknown reality. A power of which the nature remains for ever inconceivable, and to which no limits in time or space can be imagined, works in us certain effects. These effects have certain likenesses of kind, the most general of which we class together under the names of matter, motion, and force." In which sentences it is distinctly stated that I have throughout regarded matter, under the form present to consciousness, as a symbol—a certain conditioned effect wrought in us by the unknown power; and I have gone on to say that "the interpretation of all phenomena in terms of matter, motion, and force is nothing more than the reduction of our complex symbols of thought to the simplest symbols; and when the equation has been brought to its lowest terms the symbols remain symbols still."
It will scarcely be believed, and yet it is true, that notwithstanding all this Mr. Guthrie ascribes to me the vulgar conceptions of matter and motion; argues as though I really think they are in themselves what they seem to our consciousness; and proceeds to criticise my views on this assumption. He ignores the conspicuous fact that matter and motion are both regarded by me as modes of manifestation of force, and that force, as we are conscious of it when by our own efforts