172 



1 DESCENT OF MAN ' — EXPRESSION. 



[1872. 



an eminent degree," namely, " the insatiable longing to dis- 

 cover the causes of the varied and complex phenomena pre- 

 sented by living things." He adds that in the case of the 

 author " the restless curiosity of the child to know the ' what 

 for ? ' the ' why ? ' and the ' how ? ' of everything " seems 

 " never to have abated its force." 



A writer in one of the theological reviews describes the 

 book as " the most powerful and insidious " of all the author's 

 works. 



Professor Alexander Bain criticised the book in a post- 

 script to the ' Senses and the Intellect ; ' to this essay the 

 following letter refers :] 



C. Darwin to Alexander Bain. 



Down, October 9, 1873. 



My DEAR Sir, — I am particularly obliged to you for having 

 sent me your essay. Your criticisms are all written in a 

 quite fair spirit, and indeed no one who knows you or your 

 works would expect anything else. What you say about the 

 vagueness of what I have called the direct action of the 

 nervous system, is perfectly just. I felt it so at the time, and 

 even more of late. I confess that I have never been able 

 fully to grasp your principle of spontaneity,* as well as some 

 other of your points, so as to apply them to special cases, 



* Professor Bain expounded his 

 theory of Spontaneity in the essay 

 here alluded to. It would be im- 

 possible to do justice to it within 

 the limits of a foot-note. The 

 following quotations may give some 

 notion of it : — 



" By Spontaneity I understand the 

 readiness to pass into movement, 

 in the absence of all stimulation 

 whatever; the essential requisite 

 being that the nerve-centres and 



muscles shall be fresh and vigorous. 

 .... The gesticulations and the 

 carols of young and active animals 

 are mere overflow of nervous 

 energy ; and although they are very 

 apt to concur with pleasing emotion, 

 they have an independent source. 

 .... They are not properly move- 

 ments of expression ; they express 

 nothing at all except an abundant 

 stock of physical power." 



