82 THE FOUNDATIONS OF SCIENCE 



surface of the body to the brain, and movements 

 are carried out in response to other impulses which 

 travel from the brain along another set of nerves. 



Different parts of the brain have been shown 

 by physiologists to play different functions. But 

 the co-ordination and harmonious use of different 

 functions needs a special nervous mechanism ; thus 

 the third convolution of one or other hemisphere 

 of the brain is concerned with the correlation of the 

 movements of the throat and larynx, which occur 

 in speech, and any injury to that convolution results 

 in aphasia, or loss of the power of speech. It seems 

 likely that the co-ordination and grouping of ideas 

 required in the high mental processes, is different in 

 kind to the simple constituents, and is more than 

 the mere aggregation of those constituents. 



Evidence shows that to every psychological state 

 there exists a corresponding physiological process 

 in the brain, and to every physiological process 

 appropriate physical and chemical changes in nerve 

 substance. 



This psycho-neural and psycho-physical parallelism 

 is a matter of observation and experiment, and is 

 one of the joint conclusions of psychology and physi- 

 ology. It is unnecessary for the purposes of science, 

 psychological or physiological, to frame any hypo- 

 thesis as to whether or no the subjective processes 

 of consciousness are directly connected with the 

 objective phenomena of nerve-change which accom- 



