MATTER AND FORCE, IN PHYSICAL PHENOMENA. 35 



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whether similar or different in kind which properties 

 and relations brought into action by what we call the 

 forces of nature, give origin to all the motions, combi- 

 nations and forms of matter, living and lifeless, which 

 we see around us. Few of these general definitions in 

 science have much real value. That just given ex- 

 presses at least all the essential facts ; and if omitting 

 one recent doctrine, viz., that it belongs to all material 

 atoms to be ever in motion, this omission is justified 

 by the impossibility of ever reaching the conclusion by 

 proofs. 



If it be difficult to define Matter, not less difficult 

 is it to give an unexceptionable definition of Force. 

 The very word carries with it a harsh compulsion of 

 use. We cannot dispense with some such term in 

 physical science, nor find perhaps in common lan- 

 guage any that is better. The need is to express a 

 power, or powers immaterial for aught we can affirm 

 to the contrary by which matter is put and kept in 

 state of motion or change. Difficulties of conception, 

 ambiguities of language, and problems imperfectly 

 solved, meet us here at the very threshold. One such 

 question I have already noticed. Are these forces or 

 powers, engaged in the actions of matter (and we shall 

 see how numerous are the forms they assume), really 

 distinct from it? or are they but properties or con- 

 ditions of matter itself, evolved through the relations 

 and interchanges of its elementary parts, and mutually 

 convertible, so that action or force is never lost or 

 lessened in total amount, but simply translated from 

 one form to another ? Modern science shows a leaning 



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