388 THE POPULAR SCIENCE MONTHLY. 



"matter, then, in its ultimate nature, is as absolutely incomprehensible 

 as space and time." In the second part of the work, in chapters treat- 

 ing 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 indestructibil- 

 ity 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 indestruc- 

 tibility of matter, is really known to us in terms of force ; . . . that 

 which defies suppression in thought, is really the force which the mo- 

 tion 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 mo- 

 tion 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 uni- 

 formities 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 phe- 

 nomena in terms of matter, motion, and force is nothing more than 

 the reduction of our complex symbols of thought to the simplest sym- 

 bols ; 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 mat- 

 ter 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 



