simply by withholding from the brain all stimulation by 

 means of the senses was realised." 



It now remains for us to consider how, side by side with 

 the increasing complexity in the relations of nerve-centres, 

 the functions of mind are built up from the simpler forms 

 of mental activity. We have to discuss the three functions 

 of the mind, namely, the intellect, the emotions, and the 

 will, as well as the difference between the me and the not- 

 me — myself and the outside world. Mere discrimination 

 is manifested in plants. The radicle, for examj^le, always 

 seeks the moist earth ; the expanding leaves seek the sun 

 and follow his course. In the evolution of the animal 

 series more or less conscious discrimination follows on the 

 differentiation of life-stuff into more and more definite nerve- 

 tissue and more and more associated nerve-centres. 



We have seen that particular stimuli foUow particular 

 nerve-tracts and are associated in particular centres. Centres 

 of specialised sensation are acquired by the developing 

 organism. Now, just as the phonograph rej)eats in fainter 

 terms such vibrations of sound as it has registered, so do 

 the nerve-centres become capable of repeating under stimu- 

 lation the sensations that have traversed them. Thus did 

 Hamlet reproduce his kingly father. ' ' My father, methinks 

 I see my father." " Where, my lord?" " In my mind's 

 eye, Horatio." This function is memory. Memories, like 

 sensations, fuse themselves into clusters. Constituents of 

 memories of similar kinds also associate themselves together 

 into abstract ideas. What is common to many experiences 

 becomes separated in the mind from the experiences in 

 which it is primarily found. For example, out of our 

 manifold experiences of the properties of bodies we differ- 

 entiate such abstract ideas as heat, light, weight. By 

 reason of the associations of experience, the recognition of 

 one quality of an object is sufficient to stimulate the facul- 

 ties to the reproduction of aU the qualities with which it is 

 naturallj' united in the mind. Thus, I see a round yellow 

 body which I believe to be an orange. The sight of it 

 revives past impressions of touch, and taste, and smeU, and 

 hence I acquire what may be called the perception of an 

 orange. This process takes place so rapidly that the com- 

 bined effect is practically a single act of the mind. Having 

 thus shown how the intertwining strands of nervous acti- 

 vity give us sensation, memory (that is to say, the revival 

 of past registered imi^ressions), perception, and abstract 



