MATTER AND FORCE, IN PHYSICAL PHENOMENA. 37 



The subjection of both matter and force, in the 

 common comprehension of the terms, to this great law 

 of indestructibility, and the correlation of certain 

 forces in every act of physical change, press upon us 

 the conclusion that they are in their very nature a 

 necessity to each other a phrase the most positive we 

 are entitled to use in a matter thus perplexing to all 

 philosophy. Force, apart from something on which it 

 acts, is an unmeaning word. Boscovich, as well as 

 some later philosophers, have sought indeed to give to 

 it a more distinct identity ; and to regard all material 

 phenomena in reference to centres or lines of force as 

 existences per se. Such mode of regarding the subject 

 has a determinate value, considered as a method of 

 enquiry. In like manner, motion may be dealt with 

 mathematically, apart from matter or force. But 

 neither in the so-called science of kinematics, nor in 

 the doctrines of abstract force, do we find a solution 

 of those profound problems which these several rela- 

 tions involve. We cannot separate, save for especial 

 purposes of enquiry, things thus closely and indissolubly 

 bound together in the natural world. 



I have spoken of this relation of matter and force 

 as one of mutual necessity of existence. It has been 

 sought by some, as already stated, to carry the identity 

 farther, and to consider each form of force as a par- 

 ticular mode or condition of matter. This conception, 

 if it could be generalised as a truth, would bring us 

 nearer to the kernel of the question. But we are still 

 far from such attainment, and fresh obstacles occur at 

 every step. Granting that the states and changes of 



