134 HABIT AND INTELLIGENCE. [cHAP. 



the same power belongs to many worms, which are much 

 more highly organized than the hydra; but in no verte- 

 brate animal does this power extend further than to the 

 reproduction of lost parts ; and in man, and other warm- 

 blooded animals, it usually extends, in mature life at least, 

 only to the healing of wounds. Thus, the higher the 

 organism, the less are the parts able to do without each 

 other. 



I have used an analogy drawn from the science of man's 



social relations to illustrate the unlikeness of structure and 



separation of function between the various parts of the 



organism; and I may use another analogy from the same 



science to illustrate the mutual dependence of parts, and 



the combination of their actions, which is the result of 



that unlikeness. The separation of their functions is 



called the physiological division of labour: their mutual 



Physiolo- dependence, and the combination of their action, may be 



triplication dialled physiological centralization. In the organism, as in 



or combi- human society, division of labour is necessarv to com- 



nation. , • . , , . . , , . "^ 



bmation ; and combination (or centralization, as it is called 



in politics ^) is necessary to division of labour. It appears 



to be a general law, grounded in the nature of things, that 



Special high perfection for any sjDecial purpose is in a great degree 



inanorgau incompatible with adaptation, or adaptability, to a variety 



^^atibie^' ^^ purposes. This is true alike of tools, of members of the 



with gene- living Organism, and of men. It is impossible, for instance, 



bility.*^*'^" -^^^ ^ hammer and a plane to do each other's work. It is 



inconceivable that the hand and the eye should exchange 



functions. And it is a famiHar remark, that a man who has 



attained to perfection in some mechanical — and perhaps 



I may add, in some intellectual — employment is thereby 



in a great degree incapacitated from any employment that 



needs nothing but the power of doing a variety of work 



1 I ought perhaps to remark here that any argument in favour of 

 political centralization which may be based on this analogy is not only 

 too far-fetclied (to use a njost appropriate colloquial metaphor) to be 

 of much practical value, but it is utterly vitiated by this difference, which 

 is practically all-important, that in the living organism the parts exist 

 for the whole, but in society the whole exists for the parts — society exists 

 for its members. 



