THE NERVOUS SYSTEM AND TEE INTELLECT. 



269 



formation, misunderstood by all who have studied r 

 the theory of music up to this day, introduced 

 into their works a confusion from which Science 

 only made its escape when it thought of dividing 

 ancient acoustics into two parts : one, which 

 studies the vibratory movements of bodies, the 

 theory of instruments, and which is in fact only 

 a part of mechanics ; and the other, which deals 

 with musical perceptions themselves, the theory 

 of the harmony of the voice. This science has 

 received the name of " physiological acoustics." 

 The other might be studied by a deaf-mute ; but 

 this demands as sensitive an ear as that of a Ra- 

 meau or a Helmholtz, 



We see whither all this leads us. This world, 

 which seems to us full of sound and uproar, is 

 silent, dumb as death. Everything is in agitation 

 and vibration about us, but in absolute stillness. 

 To become sounds, these motions need to find an 

 ear to strike on, a nervous system which trans- 

 forms them. Paleontologists, rather poets than 

 practically acquainted with life, have attempted 

 to describe the continents in the earliest ages of 

 the world, before the appearance of any life, re- 

 sounding with peals of thunder, the roar of the 

 waves, the bellowing of volcanoes. All very 

 grand, but very far from being physiologically 

 true. Even thunder is dumb whenever there is 

 no ear to be troubled by the vibrations of the air. 

 The world was the abode of silence until a ner- 

 vous system like our own came into existence. 



The illustration offered by hearing is, no 

 doubt, the best that could be given, because an- 

 other sense, that of touch, aids in some degree to 

 enlighten us as to the acoustic illusion ; but it is 

 probable that sight as well as hearing only gives 

 us a more or less exact translation of the lumin- 

 ous world, and that colors, particularly, have no 

 existence outside of our senses, any more than 

 musical sounds have. Unfortunately, we have 

 not here, as in the case of hearing, a method of 

 detection by the touch. All that can be conject- 

 ured with any probability is, that the external ma- 

 terial fact which the eye transforms into luminous 

 sensations must be nearly of the same nature with 

 that which produces on the skin those other sen- 

 sations known as those of heat and cold. 



There is nothing extravagant in the supposi- 

 tion that other planets are inhabited by reason- 

 able beings like man ; but if their organs are 

 different — and the high probability is that they 

 would be so — they certainly see and conceive 

 the world very differently from ourselves. Life 

 among them may be governed by the same laws. 

 They may even have a brain exactly like ours, 



and yet may get an entirely different conception 

 of the same external world, depending on the 

 organs they possess for collecting and transform- 

 ing impressions from without. Even around us, 

 when we perceive in animals organs similar to 

 our own, we can infer thence with some proba- 

 bility that they see, hear, smell, feel heat and 

 cold, like ourselves; but whenever the organs 

 designed to give us these sensations disappear, 

 or become unrecognizable, we can no longer have 

 any notion of the extent or the nature of the im- 

 pressions that strike their nervous system. It is 

 by no means certain that insects, in which the ear 

 has not yet been positively discovered, can hear. 

 Several of them indeed, like the cricket, seem to 

 call each other by a musical cadence, a sharp 

 sound causes them to fly off; but we do not 

 know whether they perceive those quiverings of 

 the air as acoustic sensations, in the way that 

 our ear does, or merely as a sensation of touch, 

 through organs of especial delicacy, like a light 

 leaf set dancing by the noise of a distant pistol- 

 shot. We know that insects are sensitive to 

 light; but the nature of that sensitiveness is a 

 problem to us. It is very improbable, at any 

 rate, that with their many-lensed eyes they per- 

 ceive an image of external objects like that which 

 our eye gives us, with its wholly different con- 

 struction. The world must show to them, in 

 quite another aspect than that it bears to us, by 

 great masses of bright and dark ; the bee, prob- 

 ably, has a very imperfect perception of the love- 

 ly outlines of the flower from which it is sucking 

 honey. 



This transformation of natural forces into 

 nervous acts always takes places in a portion of 

 gray matter, even though this consists of a single 

 nerve-cell. Need it be added that, even' if we 

 should succeed in fixing positively the seat of 

 such transformation, the fact itself remains for 

 us the unknown ? The word " transformation " 

 is but an approximation. Words necessarily fail 

 us in describing acts that can neither be under- 

 stood nor verified, of which we merely have the 

 consciousness. However this may be, and mak- 

 ing the largest allowance for our ignorance on 

 this point, it may be said that the whole discharge 

 of function by the nervous system, the whole of 

 intellectual life, is summed up in these two acts . 

 transformation by the gray matter, transmission 

 by the nerve-tubes. A nerve excited at one end 

 communicates this stimulus to the other extrem- 

 ity, where it assumes a new and a purely nervous 

 character. This act in its turn excites, further 

 on, a second act distinct from the first, and so 



