108 SUPER-ORGANIC EVOLUTION 



of civilisation, nor the other much more delicate 

 history called by Taine "the philosophy of art." 



Nothing more explicit could be desired. 



A change of pressure or composition in the 

 blood is all that is needed, a modification in the 

 amount of heat, or in the amplitude of lymphatic 

 sheaths which cover the grey substance, for a 

 brain to lose its integrity, and thereby the virtue 

 of which it is capable. It is enough that the 

 mielina or that the interstitial cement should 

 modify the histo -chemical conditions, or be badly 

 distributed, for the nerve-currents to cease to be 

 fully transmitted and diffused throughout the brain, 

 ideas thus losing their precision, their energy ; 

 Nature no longer having therefore a faithful 

 substance to register her phenomena in the same 

 series and tonality in which they are produced, 

 the parallelism, the concordance cease, and, as 

 the human intelligence has lost contact with its 

 true guide and motor, society degenerates. 



The mens sana in corpore sano of the Romans 

 meant nothing else than this. People in perfect 

 health practised every virtue ; arts, industries, and 

 science flourished, because the mens sana enjoyed 

 its fullest completeness, as it preserved its integrity 

 and its relation to the external medium, the pro- 

 pelling energies of which were registered clearly 

 and precisely in the brain. When mankind, on 



