822 ANATOMY OF VERTEBRATES. 



centres, producing the ideas of the dead man's speech :— " Why 

 hast thou disquieted me, to bring me up ?" l Qu. Were the 

 centres radiating these acoustic lines of force material or spiritual ? 



Substitute the living for the dead Prophet, and it will be said 

 that the points whence the rays of light converged to produce his 

 image in the beholder are ' material ' because ' tangible ; ' in the 

 case of the ' spirit of Samuel ' not. Had Saul stretched forth his 

 hand to grasp the vision it would have met no resistance. Let 

 us, then, analyse the sensations from tangible lines of force. I 

 stretch forth the sum of forces called ' hand,' and exercise part of 

 them in a way and direction called ' pressure,' deriving the sense 

 or idea of such act by my lines of force being opposed by other 

 lines of force. To the extent to which my forces overcome the 

 opposing forces, I have an idea of a something giving way; when 

 my lines of force are overcome by the opposite lines of force, I 

 have the idea of a hard or resisting surface. But all that I 

 know, after ultimate analysis, is the meeting of opposite forces ; 

 of the centres respectively radiating such force I know nothing ; 

 and if I did or could know anything I cannot conceive that I 

 should get a clearer idea of ' touch ' than as a relation of certain 

 lines of force acting from centres, which may as well be ' im- 

 material ' as ' material ' for any intelligible notion I can frame of 

 those verbal sounds. 



If a blade of metal could move itself to and fro in striving to 

 cleave the space between excited electro-magnetic poles, and 

 could tell us its sensations, they would be those of sawing its way 

 through a substance like cheese ; but there is no visible impedi- 

 ment : nor, were luminous undulations to vibrate from the hin- 

 drance as from the plane of force resisting the pressing finger, 

 would the hindrance be less ' immaterial.' Similarly, if lines of 

 thought-force were visible, the ' ghost' would not on that account 

 be more ' material.' 



The ideas excited by the act of pressure are those of the • ex- 

 ertion of force ' and the ' resistance of force ; ' if these ideas be 

 analysed they include those of the direction of force in lines from 

 centres or points. Further than this, my mind, or thinking faculty, 

 cannot go ; i. e. can have no clear ideas : I cannot feel that I 

 know more about the matter by calling the ( centres of force ' 

 ' material atoms ' or ' immaterial points,' and am resigned to rest 

 at a point beyond which Faraday 2 did not see his way. 



Having evidence of the opposing force acting in lines from cen- 

 tres distinct from and outside of those volitional centres called 



1 1 Sam. xxviii. 15. 2 cccxxxvn." p. 119. 



