ASSOCIATION. 667 



of summation of excitements, eacli incomplete or latent in 

 itself, into an open resultant.* The process h, rather than 

 c, will awake, if in addition to the vibrating tract a some 

 other tract cZ is in a state of sub-excitement, and formerly 

 was excited with h alone and not with a. In short, we may 

 say: 



The amount of activity at any given point in the brain-cor~ 

 tex is the sum of the tendencies of all other points to discharge 

 into it, such tendencies being proportionate (1) to the number of 

 times the excitement of each other point may have accompanied 

 that of the point in question; (2) to the intensity of such excite- 

 ments ; and (3) to the absence of any rival point functionally 

 disconnected ivith the iirst point, into ivhich the discharges might 

 be diverted. 



Expressing the fundamental law in this most compli- 

 cated way leads to the greatest ultimate simplification. 

 Let us, for the present, only treat of spontaneous trains of 

 thought and ideation, such as occur in revery or musing. 

 The case of voluntary thinking toward a certain end shall 

 come up later. 



Take, to fix our ideas, the two verses from ' Locksley 

 Hall ' : 



"I, the heir of all the ages in the foremost files of time," 



and — 



" For I doubt not through the ages one increasing purpose runs." 



Why is it that when we recite from memory one of these 

 lines, and get as far as the ages, that portion of the other 

 line which follows, and, so to speak, sprouts out of the ages, 

 does not also sprout out of our memory, and confuse the 

 sense of our words ? Simply because the word that fol- 

 lows the ages has its brain-process awakened not simply by 

 the brain-process of the ages alone, but by it plus the brain- 

 processes of all the words preceding the ages. The word 

 ages at its moment of strongest activity would, per se, indif- 

 ferently discharge into either 'in' or 'one.' So would 

 the previous words (whose tension is momentarily much 

 less strong than that of ages) each of them indifferently dis- 



* See Chapter III, pp. 82-5. 



