AND ITS SELF-CONSERVATION. 55 



It is to be further noted that physical science has long 

 used forms of expression clearly implying the insepara- 

 bility of reality and manifestation. Certain of the ' ' prop- 

 erties of matter" have been classed as essential an 

 expression which can mean nothing else than that these 

 properties are the very essence of matter; that matter 

 exists in and through these properties, and could have no 

 existence without or apart from them. This, indeed, we 

 have seen to be the case in our tracing of the simplest 

 relations necessarily involved in the objects of sense-per- 

 ception, which are, in general, the sum of things extended 

 or characterized by externality. 



And yet physical science has not been able to prevent 

 the re-appearance of the shadowy nqumenon within its 

 own domain. For, from the unquestionably just opinion 

 that there can be no action save as there is something 

 to act upon, the conclusion has been leaped to that force 

 can act only upon matter as a something apart from 

 force. 



Of course physicists have not failed to note the contra- 

 diction involved in this conception. Thus Thomson and 

 Tait, in their "Elements of Natural Philosophy" ( 173), 

 after remarking that they "cannot, of course, give a 

 definition of matter which will satisfy the metaphysician," 

 proceed to say that " 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." To 

 which they immediately add that "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 of all our senses, and certainly of the ( mus- 

 cular sense.' " 



