PRIMARY CONCEPTS OF MODERN SCIENCE. 107 



has ever written is its practical refutation — is too obvious, almost, to 

 require pointing out. 



While the example just discussed was a case of absolute incon- 

 ceivability, the other instances given by Mill are cases of true relative 

 inconceivability. The first is that of antipodes which were long held 

 to be impossible, and are now not only readily conceived as possible, 

 but known to be real. This is true enough, but it finds its explana- 

 tion, not in the law of inseparable association to which it is referred 

 by Mill, bat in the fact that our ancestors held an erroneous concept 

 of the action of gravity. They supposed that the direction in which 

 gravity acted was an absolute direction in space ; they did not realize 

 that it was a direction toward the earth's centre of gravity ; down- 

 ward to them meant something very different from the sense we at- 

 tach to that word. With this erroneous concept they could not recon- 

 cile the fact that the force of gravity held our antipodes in position 

 as well as ourselves ; nor can we. But we have a juster concept of 

 gravity, and the mode and direction of its action ; the spurious notion 

 with which the notion of antipodes was inconsistent, has been re- 

 moved, and the inconceivability of antipodes is at an end. 



Similar observations apply to Mill's remaining example (which is 

 to us the most interesting, and that for the sake of which I have car- 

 ried the discussion of this dry subject to this length) of the incon- 

 ceivability of actio in distans, to which I have already alluded. The 

 true source of our inability to conceive actio in distans is, I trust, now 

 apparent. This inability results from the inconsistency of this con- 

 cept with the prevailing concepts respecting material presence. If 

 we reverse the proposition, that a body acts where it is, and say that 

 a body is where it acts, the inconceivability disappears at once. One 

 of the wisest utterances ever made on this subject is the saying of 

 Thomas Carlyle (quoted by Mill himself in his " System of Logic," in 

 another connection) : " You say a body cannot act where it is not ? 

 With all my heart ; but, pray, where is it ? " Of course, a reconstitu- 

 tion of our concepts of material presence, in the sense here indicated, 

 would be in utter conflict with the theory of the mechanical construc- 

 tion of matter from elements which are absolutely limited, hard, un- 

 changeable, and separated from each other by absolutely void spaces. 

 It is significant that nearly all the efficient laborers in the quarries 

 of physical science vaguely feel, if they do not distinctly see, that such 

 a reconstitution is necessary. Such a feeling was at the bottom of 

 Faraday's attempt to construct matter out of the convergence and 

 intersection of mere lines of force, so as to secure to each point of 

 intersection (or, in the language of Faraday, to each centre of force) 

 a virtual omnipresence, the extent of the lines of force being infinite. 



I may be permitted to say, at the end of this long but unavoidable 

 excursion into the regions of logic and psychology, that the doctrine, 

 according to which there is no warrant for the deliverances of our 



