THE NERVOUS SYSTEM AND THE INTELLECT. 



271 



ress, since they employ a longer time in reaching ' 

 us. If the mind is occupied with something else, 

 a serious burn may be inflicted before we think ] 

 to draw the hand back. A man in deep reflec- 

 tion closes his eyes, so that luminous impressions 

 from without may not oppose the inmost nervous 

 transmissions which are taking place at the seat 

 of his thought. In some cases, very close appli. 

 cation at last even extinguishes all perception 

 foreign to the subject that absorbs us. The his- 

 tory of all absent persons proves this, the anecdote 

 of Archimedes among others, whom the soldier's 

 voice could not distract from his problem — a 

 story physiologically true. 



Between the currents ascending from the spi- 

 nal cord and those going out from the brain, the 

 conflict may be said to be permanent. There is 

 an' antagonism, an almost constant struggle for 

 influence, between the two centres, the one the 

 seat of the higher faculties characterizing ani- 

 mal life, the other ruling the lower functions of 

 vegetative life. It is this which moralists have 

 called, in reasonable enough terms in this case, 

 the spirit and the flesh. The only inquiries of 

 philosophers into the mechanism of our passions 

 which have any importance, belong to the ac- 

 count, very often given already, of these relations 

 between the moral and the physical. Physiolo- 

 gists, in their turn, study and verify that antago- 

 nism, without, however, explaining it any better 

 than moralists or philosophers have done, while 

 still seeking for its precise seat. Sometimes it 

 occurs that currents coming from the spinal cord 

 conceal, thwart, or destroy, those that flow down 

 from the brain, and sometimes the reverse hap- 

 pens. A prick excites a double current, as we 

 have seen, one ascending to the brain to turn into 

 a perception, and the other resulting at last in a 

 movement of the hand ; but it may occur that a 

 third current, issuing from the seat of will in the 

 brain, annuls the second, while permitting the 

 first to continue ; as in the story of the Roman 

 who let his hand burn, in presence of Porsenna 

 the Etruscan, and in the histories of certain mar- 

 tyrs. In the case of others, and the greater 

 number, it would seem that the perception of pain 

 was rather extinguished by fixed expectation of 

 the heavenly crown promised them than con- 

 trolled by an effort of the will. A man in whom 

 the voluntary nervous currents should control all 

 others, might be said to be the man truly master 

 of himself; but such natures, if they exist at all, 

 are in any case very rare, except in the pages of 

 novelists, who always find in them a type as un- 

 natural as it is attractive for the many. All of 



us, more or less, are subject to that rather shame- 

 ful slavery in which our organs hold our mind. 

 In spite of us and of all our efforts, our heart 

 sometimes beats faster than we choose, a blush 

 that is often false tinges our cheek, tears start to 

 our eyes when we would jealously hide all emo- 

 tion ; bad digestion is reflected in our mental lu- 

 cidity, and gloom under the influence of hypo- 

 chondriac disorder is not wholly a mistake of 

 ancient medicine. Intelligence, reason, imagina- 

 tion, the noblest faculties in man, are dependent 

 alike on a multitude of external influences and of 

 secret influences as numerous, flowing from his 

 organs. 



IV. 



Every impression from without, every exter- 

 nal contact transformed, as has been said, into an 

 unconscious sensation in the spinal cord, must, 

 in order to become a conscious perception and 

 to reach our understanding, be transmitted, to a 

 point in the brain known to anatomists under the 

 name of the optic layers. Observation of the dis- 

 eased, as well as experiment, puts this beyond 

 question. The destruction of an optic layer, 

 which is common in apoplexies, necessarily in- 

 duces the destruction of all sensation on that side 

 of the body with which it is in connection. We 

 know, through equally undeniable facts, that 

 every volition transmitted to the members that 

 execute it sets out from two other masses of gray 

 matter designated in the brain by the name of 

 " striated bodies." The perfection of these stri- 

 ated bodies is essential for the perfection of the 

 faculty we have of moving our limbs at pleasure. 

 The striated bodies, however, are not the seat of 

 the act of volition properly so called, for the apo- 

 plectic subject who has suffered the loss of these 

 organs still tries to put out his hand or foot, but 

 is unable to do so-. It is probable that the act 

 of volition undergoes, in these organs, only a first 

 transformation, which requires several other suc- 

 cessive ones in the cerebellum and the spinal 

 cord, these being definitely completed by an har- 

 monious contraction of the muscles of the limbs. 

 But is it merely the anatomy and the disposition 

 of the nervous filaments which lead to the supposi- 

 tion that this must be so ; for all these acts, in- 

 cluding the initial acts of the striated bodies, are 

 absolutely unconscious, and we should even be 

 obliged to guess at it, before seeking to prove by 

 experiments on animals whether we are in the 

 wrong. 



Between the perceptions, of which the optic 

 layers may be called the organs, and the execu- 

 tion of the intended motions, of which the origin 



