MATTER 245 



who will honestly ask himself what he conceives by matter 

 will find that an answer is impossible, or that in attempt- 

 ing one he is sinking deeper and deeper into the 

 metaphysical quagmire. 



Proceeding further, we naturally turn to the little work 

 termed Matter and Motion, by Clerk-Maxwell, one of the 

 greatest British physicists of our generation. This is 

 what he writes of matter : — 



" We are acquainted ivith matter only as that ivhich 

 may have energy communicated to it from other matter, and 

 which may in its turn communicate energy to other matter." 



Now this appears something definite ; the only way in 

 which we can understand matter is through the energy 

 which it transfers. What, then, is energy ? Here is 

 Clerk-Maxwell's answer : — 



" Energy, on the other hand, we know only as that which 

 in all natural phenomena is continually passing from one 

 portion of matter to a7iotherr 



All our hopes are shattered ! The only way to under- 

 stand energy is through matter. Matter has been defined 

 in terms of energy, and energy again in terms of matter. 

 Now Clerk-Maxwell's statements are extremely valuable 

 as expressing concisely the nature of certain conceptual 

 processes, by aid of which we describe certain phases of 

 our perceptual experience, but as defining matter they 

 carry us no further than the statement that matter is that 

 which moves. 



We will now turn to the famous Treatise on Natural 

 Philosophy of Sir William Thomson (now Lord Kelvin) 

 and Professor Tait — the standard work in the English 

 language on its own branches of physical science. These 

 writers, in ^ 207, tell us : — 



" We cannot, of course, give a definition of matter 

 which will satisfy the metaphysician, but the naturalist 

 may be content to know matter as that which can be 

 perceived by the senses, or as that which can be acted 

 upon by, or can exert, force. The latter, and indeed the 

 former also, of these definitions involves the idea of force, 

 which, in point of fact, is a direct object of sense ; probably 



