THE NERVOUS SYSTEM AND CONSCIOUSNESS. 157 



Permit me to repeat the statement that there is no reasoning here 

 along the " high-priori " road of inconceivability. I see no more incon- 

 ceivability in supposing that a brain-change should be followed by a 

 thought than that it should be followed by an increased secretion. The 

 thing needed is, to know the fact in the case. Are brain-changes 

 transformed into consciousness, or does the soul, on occasion of these 

 changes, respond in its peculiar language ? 



The brain-changes, as we know them and must know them, consist of 

 attractions, repulsions, motions, and co-ordinations of the brain-particles. 

 These, according to the physiological materialist and the young physi- 

 cian, are transformed into states of consciousness, which states are not 

 material changes, but separated from them by a chasm " intellectually 

 impassable." It has been wisely said that the position which a thor- 

 ough-going scientific evolution ought to defend is this : thoughts, feel- 

 ings, volitions, any and all states of consciousness, have no existence 

 for physical science. Indeed, the annoyance caused by consciousness as 

 a useless "surplusage" is nowhere more strikingly illustrated than in 

 the following passage from Professor Huxley's paper " On the Hypothe- 

 sis that Animals are Automata." The author writes : " Though we 

 may see reason to disagree with Descartes's hypothesis that brutes are 

 unconscious machines, it does not follow that he was wrong in regard- 

 ing them as automata. We believe, in short, that they are machines, 

 one part of which (the nervous system) not only sets the rest in motion 

 and co-ordinates its movements in relation with changes in surround- 

 ing bodies, but is provided with special apparatus, the function of 

 which is the calling into existence of those states of consciousness 

 which are termed sensations, emotions, ideas. It may be assumed, then, 

 that molecular changes in the brain are the causes of all the states of 

 consciousness in brutes. Is there any evidence that these states of 

 consciousness may, conversely, cause those molecular changes which 

 give rise to muscular motion ? I see no such evidence. The frog 

 walks, hops, swims, quite as well without consciousness as with it, and 

 if a frog, in his natural state, possesses anything corresponding with 

 what we call volition, there is no reason to think that it is anything 

 but a concomitant of molecular changes in the brain which form part 

 of the series involved in the production of motion. The consciousness 

 of brutes would appear to be related to the mechanism of their body 

 as a collateral product of its working, and to be as completely without 

 any power of modifying that working as the steam - whistle which 

 accompanies the work of a locomotive-engine is without influence upon 

 its machinery. Their volition, if they have any, is an emotion (?) 

 indicative of physical changes, not a cause of such changes. It is quite 

 true that this reasoning holds equally good of men, and therefore that 

 all states of consciousness in us, as in them, are immediately caused by 

 molecular changes of the brain-substance. It seems to me that, in men 

 as in brutes, there is no proof that any state of consciousness is the 



