170 CORRELATION OF PHYSICAL FORCES. 



been rather to show the relation of forces as evinced by 

 acknowledged facts, than to enter upon any detailed expla- 

 nation of their specific modes of action. 



Probably man will never know the ultimate structure of 

 matter or the minutiae of molecular actions ; indeed, it is 

 scarcely conceivable that the mind can ever attain to this 

 knowledge ; the monad irresolvable by a given microscope 

 may be resolved by an increase in power. Much harm has 

 already been done by attempting hypothetically to dissect 

 matter and to discuss the shapes, sizes, and numbers of 

 atoms, and their atmospheres of heat, ether, or electricity. 



Whether the regarding electricity, light, magnetism, &c., 

 as simply motions of ordinary matter be or be not admissible, 

 certain it is, that all past theories have resolved, and all exist- 

 ing theories do resolve, the actions of these forces into motion. 

 Whether it be that, on account of our familiarity with mo- 

 tion, we refer other affections to it, as to a language which is 

 most easily construed and most capable of explaining them, 

 or whether it be that it is in reality the only mode in which 

 our minds, as contradistinguished from our senses, are able to 

 conceive material agencies, certain it is that since the period 

 at which the mystic notions of spiritual or preternatural 

 powers were applied to account for physical phenomena, all 

 hypotheses framed to explain them have resolved them into 

 motion. Take, for example, the theories of light, to which I 

 have before alluded : one of these supposes light to be a pecu- 

 liar rare matter, emitted from i.e. put in motion by luminous 

 bodies; a second supposes that the specific matter is not 

 emitted from luminous bodies, but is put into a state of vibration 

 or undulation, i.e. motion by them ; and thirdly, light may be 

 regarded as an undulation or motion of ordinary matter, and 

 propagated by undulations of air, glass, &c., as I have before 

 stated. In all these hypotheses, matter and motion are the 

 only conceptions. Nor, even if we accept terms derived from 

 our own sensations, the which sensations themselves may be 

 but modes of motion in the nervous filaments, can we find 

 words to describe phenomena other than those expressive of 

 matter and motion. We in vain struggle to escape from these 



