MENTAL FUNCTION 419 



metaphysical relation of these two series, for our entire object is to point 

 out some of the almost obvious facts of their relationship. 



Before doing that, however, we may merely mention some of the theories 

 of this association. These are of three sorts, two of which are monistic 

 theories and one dualistic at least for scientific purposes. The theory 

 of pure idealism maintains that the conscious series is the real one and 

 that in some incomprehensible way the bodily series is but an aspect of 

 consciousness. The opposed hypothesis, now clearly given up by 

 philosophy as a living belief, is the materialistic point of view, namely, 

 that the conscious process is only an epiphenomenon of the bodily life, 

 the product of the activity of protoplasm. The dualistic theory of the 

 relations of body and mind supposes, at least for scientific purposes, that 

 there are two kinds of series running along always just side by side but 

 of essentially different natures. When these two series are postulated 

 as entirely independent of each other, we have the theory of psycho- 

 physical parallelism. When they are assumed to be continually inter- 

 acting, we have the theory of interaction. 



Some biologists have supposed that only man was conscious, others 

 that the mental process has its basis only in the nervous system, and 

 others still that all protoplasm has consciousness as part of its life. If, 

 furthermore, there be a few who suppose that consciousness is attached 

 to the whole creation, it is no affair of ours in this connection, but 

 concerns rather the speculations of philosophy. 



We may perhaps best suggest a few of the most obvious relationships 

 of mind and body in addition to those already intimated above, if we 

 take up in turn the three aspects of the mental process, feeling, willing, 

 and knowing. Far from attempting to say how mind and body are 

 related, we only mention some of the instances in which a relation is 

 especially apparent. 



In the aspect of feeling, willing, and knowing which we call sensation 

 it is clear in what way the bodily mechanism is concerned. In the chap- 

 ter before the last we studied the sense-organs. We saw that in every 

 case physical force of some sort impinges on these thousands of sense- 

 organs on the surface aftd in the interior of the body, and that the nervous 

 impulses actuated by these movements in the afferent end-organs go as 

 influences into the central nervous system. In every case, moreover, 

 whether we can define it accurately or not, such impacts are followed by 

 reactions in the central nervous system and efferent nerve-influences 

 stream outward. There is little doubt at the present time that this 

 complicated and multifarious maze of nerve-impulses going and coming 

 everywhere through the body, forms the "basis" of the mental process. 

 Some of these nervous influences are probably directly and intensely 

 conscious to the individual, but of the others he knows nothing directly. 

 Inasmuch as sensation (based on these influences) is a conspicuous part 

 in almost every mental process, we have here a chief respect in which 

 the body and the mind are related. 



In the mental process known as feeling and emotion we have, as it 



