XIV. 



COINAGES OF THE BRAIN. 



THE means whereby we are enabled to form conceptions and judg- 

 ments of the outer world, and of our own relations thereto, form the 

 subject-matter of the most elementary study in the physiology of 

 nerves. But as the understanding of the deepest problems often 

 depends on the correctness of our primitive studies and on the 

 soundness of the beginnings of knowledge, it may be well that, in 

 studying the work of the brain, we should very briefly glance at the 

 manner and method in which body or outer world usually acts upon 

 mind, and mind in turn upon the frame it controls. Such a simple 

 study in sensation will suffice to introduce us to some interesting 

 phenomena of mind ; .and these last may prove of some service, even 

 if they may but aid us in some degree to comprehend the nature and 

 ways of our own being. 



When, under ordinary circumstances, an impression from the 

 external world reaches the outward parts of our nervous system, or 

 passes through one of those "gateways of knowledge" which we term 

 an organ of sense, it is transmitted in due course to a special part of 

 the nervous system named a nerve-centre. There the impression 

 gives rise to actions or processes which result in the production of a 

 "sensation," and commonly also of "consciousness" that is, the 

 knowledge of the why and wherefore of our acts and feelings. Apait 

 from metaphysical vagaries and subtleties, this much seems clear- 

 that any simple sensation, starting like an electric current from the 

 outer world, and passing along the wires we term nerves, to the head- 

 office or brain, gives rise therein to responsive feelings, and, it may 

 be, to corresponding and related actions in the body as well. 



Example is more potent than precept; let us therefore turn to the 

 study of a common sensation such as that of touch, by way of illus- 

 trating the ways and methods of the ordinary government of life. A 

 person aims a blow at our head, and that important region is quickly, 

 and we may add automatically, withdrawn from the threatened con- 

 tact with the malcontent. The explanation of our action is perfectly 

 clear. The impression of the moving fist was caught by the eye, 

 was modified by its passage in the form of light-rays through that 

 organ, was converted into a " sensation," was transmitted through a 

 special (optic) nerve to the brain, was therein transferred to some 

 special region of the seat of mind, and finally gave rise to the 



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