The Internal Senses. 685 



up motion in definite muscles, or in other cortical organs. The muscu- 

 lar movements to which they give rise, constitute their "expression." 

 The organs thus formed must relate to everything which makes such a 

 mark upon the brain that subsequent appropriate stimulation is able to 

 revive a recollection of it. I take it that no organ exists in the brain 

 representing an action, event or thing, unless such action or thing can, 

 under some condition, be brought to recollection. Organs come and go, 

 that is, are made and unmade by use and disuse. The more things we 

 see and hear and reflect upon, the more extensive becomes the area of 

 the cortex, the thicker it gets, the greater the number of its fissures and 

 convolutions, the greater the number of the cells. And, as in old age, 

 the muscles shrink and the senses grow dim, so the cortex loses in its 

 area, thickness and consistency. Obviously, the whole, or parts of the 

 organs are lost, and those remaining are deteriorated in functional mobility. 

 What has been said heretofore leads to the conclusion that every new 

 stimulation which reaches the cortex from without, differentiates a por- 

 tion of it, so that a restimulation of that part gives a recollection of the 

 fact which caused the differentiation, and when such recollection can no 

 longer be revived, it is evidence that the effects of the act of differen- 

 tiation have been lost. It follows, then, that all organs thus differenti- 

 ated are organs of memoiy. But we are aware of actions going on in 

 the brain which arouse in us sensations of objects that do not, as a 

 whole, resemble any one thing, or combination of things we know of. 

 They contain imitations of the elements of things in the environment, 

 but under new arrangements, forming new combinations, not exactly like 

 anything we know objectively, and yet so real as to be able to effect the 

 same sort of differentiations in the cortical substance that are made by 

 original stimuli, and which can be restimulated and recollected after- 

 ward. These interior, or wholly subjective cerebral actions, we know 

 as works of the imagination ; dreams, inventions, ratiocinations, moral- 

 izations, musical compositions, &c. There is no originality in the ele- 

 ments of these new combinations, because these have all necessarily been 

 introduced from the environment. A vast number of these rearrange- 

 ments are constantly being formed in our brains, by far the greater part 

 of which, however, leave no permanent impression there, and presuma- 

 bly effect no lasting differentiation of cerebral substance. Those which 

 do, we call "original " ideas, and they are not forgotten, at least for a 

 time. The cortical cells erected by this sort of action must constitute 

 organs as real as, and like those formed by the original incoming stimuli 

 of light, sound, &c. The motive force concerned in their construction 

 is the very same, consisting of external energy transmuted into nervous 

 force. A great amount of this sort of action goes on in even' brain, 

 the most of which receives too little attention to effect a permanent dif- 



