ioo FUNCTIONAL INERTIA 



own and Faraday's sense. Thus, where the origin 

 of illusions is being discussed, we meet with the 

 expression, ' by sheer mental inertia we cont nue 

 to interpret the exceptional cases as if they were 

 regular." * In 1900 I had explained the Miiller- 

 Lyer illusion on the principle of katabolic psychical 

 inertia. f Once again this author shows us how 

 much the notion of inertia is present to his mind, 

 for, still speaking of illusions, he says, "They 

 will remain by inertia for want of an opposing 

 force." J This is not exactly how I would express 

 it, for protoplasmic inertia maintains states in 

 spite of opposing forces. It is, however, evident 

 that modern psychology no less than animal and 

 vegetable physiology cannot do without the concept 

 of inertia. Just as in the individual character 

 psychic inertia plays so notable a part, so too, in the 

 national character does it not constitute as potent 

 a factor as affectability in moulding the destinies 

 of a race ? How is it that nations have a definite 

 course of development, maturity and decay ? They 

 rise and they fall ; the Roman Empire was not the 

 only one to do so ; Babylonia, Assyria, Persia, and 

 Greece all went through very similar cycles : they 

 grew up, they had their prime, they degenerated. 

 Something inherent rather than as due to external 

 conditions must have brought about this similarity of 

 fate : someth'ng unfolded, came to perfection, faded 

 away in these nations as it does in individuals. 



* G. M. Stratton, " Experimental Psychology," p. 104. 



f Glasgow Medical Journal , April 1901. J Ibid. p. 118. 



