562 



NA TURE 



[Oct. 25, 1877 



dualism, although he cannot directly contradict it. It is true 

 thattliis dualism is infinitely different from the ordinai7 dualism, 

 since it assigns the exclusive power to the forces ol nature, and 

 to the mind only an inactive, empty dignity, and thus hinders in 

 no way the strictly causal or materialistic conception of all 

 material occurrences, also of those wliich bring about mental 

 life. But nevertheless we would wish for a solution which cor- 

 responds more to our experiences and to our theoretical concep- 

 tions. And I believe that this solution lies very near if we 

 extend our judgment of the phenomena in organic nature to 

 those of inorganic nature as well. 



It is quite correct in Du Bois Reymond to say that we can 

 only know the material conditions of mental life, but that how 

 this results from those conditions remains a secret to us for ever. 

 But it would be an error to suppose that we generally understand 

 the origin of natural life from its causes. In all purely material 

 phenomena we find the same barrier as in the mental ones. We 

 know by experience that in the inorganic world the cause is lost 

 in the effect, but we cannot understand the nature of the transfer. 

 We know by experience that a stone thrown up into the air falls 

 to the ground, and we say that this happens because the earth 

 attract; it ; but this attraction is for us incomprehensible. 



What we do know is, that two bodies which are apart 

 act upon one another in such a way that, it there is no 

 ol stacle, they approach one another until they touch. In 

 what, however, this action consists, how it adduces the mutual 

 motion, is for us just as unintelligible, and will remain just 

 as eternal an enigma, as the origin of sensation and conscious- 

 ness from material caues. With all material, physical, and 

 chemical phenomena, we find the same. A body charged with 

 positive electricity, and another one charged with negative elec- 

 tricity, move towards each other ; two bodies similarly electiified 

 repel one another. If we say that in the former case attraction, 

 and in the second repulsion takes place, then these are only 

 short expressions which comprise whole series of similar pheno- 

 mena, but give no explanations. But we accustom ourselves to 

 such expressions ; little by little we use them so frequently and 

 easily, that we believe we really understand the phenomena they 

 designate. And that is why the view is generally held, that 

 nature in her simpler inorganic phenomena offers no difficulties 

 to our conception, whereas in reality the difficulties are every- 

 where the same in principle. 



The objection will perhaps be raised, that the two sides of the 

 question are not quite so equal as I say ; that with purely 

 material phenomena the relation between two material particles, 

 which causes their motion, is indeed incomprehensible ; that 

 with mental phenomena this incomprehensible relation between 

 the material panicles is also given ; but that something else, 

 something new is added, namely, the mental action which 

 accompanies the material phenomenon. But this objection, if 

 indeed we raise it, would be unfounded ; we should have over- 

 looked that the two sides into which we shou'd divide the mental 

 phenomenon are equally present with the purely material 

 phenomenon, only that they are not separately conceived here 

 but in one, namely, the sensation and the reaction which this 

 sensation causes. 



Tills fact, that the simplest inorganic phenomena are quite as 

 inaccessible m their origin as the most complicated occurrences 

 in the human brain, constructs the bridge which may lead us 

 to a ihonistic {linhcitliche) conce|.tion of nature. Let us start 

 from what we know — and in this case it is the complicated 

 mental phenomenon — in order to obtain from it a conception of 

 what we still ignoran of. 



We know mental life only from our subjective experiences ; 

 we know that we draw conclusions, that we remember, that we 

 feel pleasure and pain. That similar but undeveloped pheno- 

 mena I ccur wiih children and higher animals, we conclude from 

 their actions and from their somatic manifestations, which we 

 interpret as the expression of emoiion and sensation. Actual 

 proofs that even the lower animals still possess sensation, vliich 

 is only oilTerent in degree from the conscious sensation of man, 

 we have only in their movements consequent upon some irri- 

 tation, and in the important circumstance that these movements 

 upon irritation in the ascending animal classes pass through all 

 gradations upwards to the most complicated phenomena in the 

 human brain. From these irritation-movements of the lowest 

 animals we imperceptibly get to those of the unicellulrr plants 

 and of the sensitive plants, and thence to the phenomena of the 

 apparently insensible plants, which cannot be distinguished from 

 tlie phenomena of inorganic nature. Between the irritation- 

 movements of plants and animals, however, and the apparently 



insensible inorganic movements, there is no other difference but 

 this, that in the case of irritation a powerful cause acts upon 

 numberless material particles arranged in a similar manner, and 

 thus produces a movement of place or sensation which becomes 

 perceptible to our senses, while when this perceptible movement 

 is wanting, the cause of the molecular, movements, which take 

 place in several directions, is not called an irritation. 



In the higher animal world sensation is distinctly present in 

 the movements consequent upon irritation. We must therefore 

 credit the lower animals with it as well, and we have no 

 reason to deny it in the case of plants and inorganic bodies. 

 Sensation causes us to feel pleasure or displeasure. Generally 

 speaking the feeling of pleasure arises when our natural 

 inclinations are gratified, and the feeling of pain when this 

 gratification is denied. As all material phenomena are com- 

 posed of the motions of molecules and elementary atoms, 

 pleasure and pain must have their original seat in these particles ; 

 they must be caused by the manner in which these infinitesimal 

 particles are able to respond to the attracting or repelling forces 

 which act upon them. Sensation, therefore, is a property of the 

 albumen molecules ; and if we grant it in the case of albumen 

 molecules we must grant it likewise in the case of the molecules 

 of all other substances. 



Let us now consider the relation of two molecules of different 

 chemical elements (for instance that of a hydrogen molecule and 

 one of oxygen), which are at a minute distance from each other. 

 Each of them, according to the present notions of chemistry, 

 consists of two not further divisible, but yet decidedly com- 

 pound atoms. By means of its composition the atom has 

 different properties and forces, and therefore acts differently 

 (attracting or repelling) upon btlier atoms. The two molecules 

 in question experience or feel their mutual presence in a different 

 manner ; they act upon each other with different attractive or 

 repulsive power. 



Let us examine what happens in the case of a certain attrac- 

 tion, for instance, in that of a chemical one Three possibilities 

 exist : either the molecules follow their inclination and approach 

 one another, or they are condemned to rest through other forces 

 which are equal to the attraciion, or they move away from one 

 another, the forces counteracting their inclination gaining the 

 upper hand. The same three possibilities are given for a certain 

 repulsion, for instance, through heat ; the two molecules follow 

 their natural inclination and move away from each other, or they 

 remain at the same distance, or they are pushed towards one 

 another by other causes, their inclination being overcome. 



Now if the molecules possess anything which is ever so dis- 

 tantly related to sensation, and we cannot doubt it, since each 

 one feels the presence, the certain condition, the peculiar forces 

 of the other, and, accordingly, has the inclination to move and, 

 under circumstances, really begins to move, becomes alive as it 

 were, moreover, since such molecules are the elements whicli 

 cause pleasure and pain ; if therefore the molecules feel some- 

 thing which is related to sensation, then this must be pleasure if 

 they can respond to attraciion and repulsion, i.e., follow their 

 inclination or di!inclination ; it must be displeasure if they are 

 forced to execute some opposite movement, and it must be 

 neither pleasure nor displeasure if they remain at rest. 



As the molecules act upon each other with several unequal 

 attractive and repulsive forces, some of their inclinations, when- 

 ever they are in motion, are always gratified, while others are 

 offended. But these different sensations are necessarily unequal 

 with regard to condition and intensity, according as they are 

 caused by the general attraction of gravitation, by the general 

 repulsion of heat and of elasticity, by electric and magnetic 

 attraction and repulsion, or by chemical affinity. The simplest 

 organisms which we know, if I may use this expression, the 

 moiecules of chemical elements, are therefore simultaneously 

 influenced by several qualitatively and quantiiativcly different 

 sensations, which conglomerate to a total sensation of pleasure 

 or pain. 



At the lowest and simplest stage of material organisation which 

 we know, we therefore find on the whole the same phenomenon 

 as we tlo at the highest stage, where it appears as conscious sen- 

 sation. The difference is only one of gradation ; at the highest 

 stage the influences have only become so much more vivid in 

 consequence of a vast accumulation of different material particles, 

 and much more compound and intricate on account of the com- 

 plicated organisation. 



If we look upon mental life in its most general signification as 

 the immaterial expression of the material phenomena, as the 

 mediation between cause and effect, then we find it everywhere 



