THE PHYSIOLOGY OF EMOTION. 2 8i 



one, when established, cannot be disjoined, any more than that of the 

 other. Consequently, stimulation of such a group of ideas calls it 

 into action, and then arises its special feeling, depending in degree 

 upon the amount of the stimulation and the nerve-force extricated in 

 the process. And these very complex emotions may be reduced by 

 analysis to much simpler feelings to feelings of self-advantage or self- 

 detriment, the pleasure or pain which is at the bottom of all feeling, 

 of all stimulation of the nervous system strong enough to cause feeling 

 to come into consciousness. Looking upon the whole conscious brain 

 as self, its feeling varies from self-good to self-ill ; its various and 

 special portions, groups of nerve-cells and nerve-centres, being stimu- 

 lated into special feelings which are yet all of them resolvable into the 

 simple elements. If we look at the phenomena of insanity we shall 

 see this illustrated by the fact that the feelings and delusions of the 

 insane always have reference to self. 



I have traced the higher emotions up from the mere bodily feel- 

 ings, nay, even from the sensations of the special senses, and have 

 affirmed that they all vary according to the amount of stimulation 

 which each centre receives, while their quality depends on the special 

 properties of the centre or centres. The phenomena of two of the 

 senses, at any rate, confirm this view. One person hears a sound 

 which another cannot. This is because the centre of hearing in the 

 deaf person is not sufficiently stimulated by a sound, the vibrations of 

 which are too slow for him, though not too slow for the other to per- 

 ceive. Similarly, some people cannot recognize redness as a color. 

 On analyzing the color red, we find it to be the color at one end of the 

 spectrum, an inch of which gives the smallest number of waves of 

 light, and to this amount of stimulation some eyes are insensible, just 

 as the eyes of all men are insensible to the rays beyond red, which we 

 discover by the galvanometer, though they do not excite our optic 

 centres as light. As no two persons feel alike, so no two see or hear 

 alike. The centres of sight and hearing of one man are stimulated by 

 vibrations which fail to excite those of another. There may be colors 

 and there may be harmonies all around us in the universe, of which we 

 know nothing, but of which the more sensitive organs of what are 

 called the lower animals may be keenly conscious. It may be that 

 these animals are only by us called dumb because we ourselves are 

 deaf. 



The stimuli, then, which excite the nerve-centres of man, produce 

 various feelings and emotions according to the quality and properties 

 of the centre excited. But, as I have said, the feeling will vary 

 according not only to the quality of the centre, but also according to 

 the condition it may happen to be in at the time, or that to which it 

 may be brought by the stimulation it experiences. To elucidate this, 

 we must consider what we know of the physiology of nerve-structures 

 and their functions. 



