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satisfied with that account of the origination of an event which simply refers 

 it to another event immediately preceding ? Can the human mind, in its 

 self-impelled search for causes, stop short of anything other than reality, 

 endowed with powers enabling it to produce certain effects ? An examination 

 of our judgments concerning the realities presented to us, reveals the fact 

 that we are compelled to think each of them as possessing a given consti- 

 tution, as endowed with certain " qualities " and " powers." These judgments 

 we must accept as the starting points of thought ; their validity cannot by 

 us be determined in the light of higher truths ; to us they are ultimate. 

 Turning to the world of matter, let us begin with the atoms themselves — • 

 what, by the very laws of our intelligence, are we compelled to think about 

 them ? First, we think that each atom possesses certain " qualities." These 

 all have relation to space, and constitute the "primary" qualities of the 

 metaphysician. Second, we think the atoms to possess also certain 

 " powers," whose existence we apprehend not immediately as we do that of 

 the qualities, but only mediately or through their effects. Now, since each 

 atom has both qualities and powers, the theory that matter is indestructible, 

 embraces two things : — 



(1.) The conservation or persistence of material qualities. 



(2.) The conservation or persistence of material powers. 

 To regard these two doctrines as separable is unphilosophical ; they are but 

 different aspects of the one truth concerning the indestructibility of matter 

 by human agents. That this is so, is evident from the fact that is impossible, 

 even in imagination, to separate the powers from the qualities, as associated 

 together in the most elementary form, of material existence. In this 

 connection Faraday's words are very important and significant. He says : 

 " A particle of oxygen is ever a particle of oxygen ; nothing can in the least 

 wear it. If it enter into combination, and disappear as oxygen ; if it pass 

 through a thousand combinations — animal, vegetable, and mineral ; if it lie 

 hid for a thousand years, and then be evolved, it is oxygen with its first 

 qualities neither more nor less. It has all its original force, and only that." 

 To-night, Mr. Brooke has told us that " in cases of percussion, the energy of 

 a striking body may be more or less imparted to the body struck." But is 

 not this statement wholly inconsistent with the doctrine of the indestructi- 

 bility of matter ? If, when an atom of oxygen exerts one or more of its 

 powers, there is a transference of energy to some other reality, does it not 

 then cease to bo a particle of oxygen ? " Energy," says Mr. Brooke, " was 

 first defined, by Thomas Young, to be " the power of doing work," and this 

 definition does not appear to require any amendment." Now, if by " work " 

 is here meant the mere displacement of matter, either molecularly or 

 in mass, the distinction between force and energy is not a valid one. Take 

 any power— mental, vital, or material : we find that we are able to think it 

 either as unexerted or as exerted ; in other words, as power " at rest," or 

 power " in action." To denote the latter, philosophers have employed the term 

 energy ; so that energy is not the power of doing work, but power doing work, 

 power in work (tv tpyov). But this is not the only case in which we think 



