PHYSIOLOGY AND PSYCHOLOGY 121 



observation of activities of which we are con 

 scious. In making these observations we 

 deliberately disregard or abstract from the 

 whole psychological aspect of the phenomena : 

 we even take special precautions to exclude 

 psychical interference. In this way we observe 

 and analyse the physiology of the sense-organs, 

 muscular movements, breathing, the intake of 

 food and drink, etc. The methods used are 

 exactly the same as if we were investigating 

 something which is outside of direct conscious 

 control, such as the circulation, or the secretion 

 of urine ; and it is a complete mistake to de 

 scribe as psychology any such investigation in 

 which we are observing something of which we 

 are conscious. Psychology deals with person 

 ality, and observations from which all that is dis 

 tinctive of personality is rigidly excluded have 

 nothing to do with psychology. Conversely, 

 psychological investigation has no place in 

 physiology. The physiologist who treats of 

 perception and volition is going outside his 

 own subject, and sometimes does so in a 

 quite illegitimate manner, endeavouring to 

 state or explain psychological phenomena 

 in terms of a conception which cannot be 



