CHAP, ii MIND AND MECHANISM 13 



and the diaphragm, respiration follows as a matter ot 

 pneumatics. In all these cases there are indeed qualifica- 

 tions induced by more searching inquiry. Not all the 

 facts of circulation are explicable on the principles of the 

 common pump. When the dilatation and contraction of 

 the arteries, for example, are taken into account, we can no 

 longer think of the blood as circulating through a simple 

 system of elastic tubes. When all the facts are known 

 the phenomena of digestion are not found to correspond 

 accurately to the chemical laws of osmosis. Moreover, 

 in stating each of these processes in mechanical terms, we 

 have to assume certain forces which are not like those of 

 an ordinary inanimate mechanism. Nevertheless the 

 advocates of the mechanical theory of life point with 

 triumph to a series of successes. Time and again they 

 have reduced some mysterious process, which seemed 

 distinctive of living beings and explicable only by the 

 assumption of some vital force, to mechanical terms. 

 Their belief is that the residue which is at present 

 unreduced only requires further investigation to be set 

 upon the same basis. If we knew enough about the 

 structure of the heart and the nature of nerves and 

 muscular action, we should be able to state the law of its 

 pulsations in mechanical formulae. A similar extension 

 of our knowledge would explain the adaptation of the 

 arteries to the fluctuating requirements of the body, the 

 control of the respiratory mechanism by the medullary 

 centre, the absorption of foodstuff by the cells lining 

 the alimentary canal, and so forth. Finally, a still more 

 perfect knowledge would enable us to reduce purposive 

 action, artistic creation, philosophic thought to a complex 

 of mechanical changes in nervous tissue. All would be 

 recognised as mechanism if we could only know the 

 whole of the intimate structure of the body. 



In order to examine this theory and to decide what 

 part, if any, is played by Mind in modifying mechanical 

 processes, we must ask in general terms what is meant by 

 the mechanical and what sort of function we suppose 

 mind to introduce in the business of correlating vital 

 activities. Now if we take a confessedly inanimate 



