220 HEREDITY AND SELECTION IN SOCIOLOGY 



not purely physiological in their nature ; thus they are not subject 

 to — or, at any rate, are less subject to — ^the laws which govern 

 the physiological life of the organism. The quantity of food 

 necessary to the sustenance of a human being we may calculate 

 as determinable ; for although even the desires in this purely 

 physiological domain are different, according as to whether the 

 social situation of the human being is on a higher or a lower 

 level, nevertheless there is a limit to the amount of food which 

 an organism is able to assimilate. This amoimt differs according 

 to the individual, and we cannot trace an arbitrary limit hold- 

 ing good for all the individuals of the human species ; but we may 

 say that the physiological capacity for assimilation possessed 

 by each individual constitution is limited, and the quantity of 

 nutriment capable of being absorbed by it strictly determinable. 

 However, if even the materials necessary to the purely physio- 

 logical life of the organism are in each individual case deter- 

 minable ; there remains a vast number of desires which are not 

 physiological in their nature, and which are not strictly deter- 

 minable. Man differs from his predecessors in the animal world 

 precisely in that his psychological life is so immensely developed 

 as to constitute the most important part of his existence, the 

 most valuable and the most durable part. And all the desires 

 and needs of this vast sphere of human life are outside the domain 

 of physiological law, and cannot be determined by physiological 

 law. Let us take, for instance, the desire of luxury and comfort. 

 Here we have a desire very general, it would seem, in human 

 nature. How the desire for luxury has been developed in the 

 course of ages since primitive man we cannot now inquire. It 

 suffices for us that it is a desire which increases pari passu with 

 the increase of social resources, with the development of social 

 wealth. It is a desire which is psychological in its nature. And, 

 we may ask, how are we to discover the manner in which this 

 desire should vary in proportion to the profession or to the 

 value of the services rendered by the individual to society ? 



