THE EOOT-PRIXCIPLES OF MIXD. 61 



a kind of obverse reflection of the other. Turning, therefore, 

 to contemplate this presumably obverse reflection, we found 

 that in many respects it is most strikingly true that the 

 fundamental principles of mental operation correspond with 

 the fundamental principles of ganglionic operation. Thus, we 

 found that such is the case witli memory and the association 

 of ideas, both of which we found to have their objective 

 counterparts in the powers of non-mental acquisition which 

 are presented by the lower ganglia. For we found that these 

 ganglia unconsciously learn such exercises as they are made 

 frequently to perform, that they forget their exercises if too 

 long an interval is allowed to elapse between the times of 

 practising them, but that even when apparently quite for- 

 gotten such exercises are more easily re-acquired than 

 originally they were acquired. Alore particularly we found 

 that the association of ideas by contiguity presents a remark- 

 ably detailed resemblance to the association of muscular 

 movements by contiguity. For, agreeing to take ideas as the 

 objective analogues of muscular movements, we observed when 

 we thus changed the index of nervous operation from muscles 

 to ideas, that the strongest evidence was yielded of the method 

 of nervous evolution being everywhere uniform. Thus we 

 remarked that sensations, perceptions, ideas, and emotions all 

 more or less resemble muscular co-ordinations in that they 

 are usually blended states of consciousness, wherein each con- 

 stituent part must correspond with the activity of some 

 particular nervous element — a variety of such elements being 

 therefore concerned in the composite state of consciousness, 

 just as a variety of such elements are concerned in a com- 

 bined movement of muscles. Further, just as the associa- 

 tion of ideas is not restricted to a blending of simultaneous 

 ideas into one composite idea, but extends to a linking of one 

 idea with another in serial succession ; so we saw that mus- 

 cular movements exhibit a precisely analogous tendency to 

 recur in the same serial order as that in which they have 

 previously occurred. Lastly, we noted that all the patholo- 

 gical derangements which arise in the nerve-centres that 

 preside over muscular activities, have their parallels in simi- 

 lar derangements which arise in the nerve-centres that are 

 concerned in mental activities. 



Having thus dealt with the Physical Basis of Mind, we 

 passed on in the next chapter to consider the Eoot-principles 



