272 NATURE AND MAN. 



capture it ; when, also, we see that it possesses organs, which, 

 though framed on a different plan from our eyes, have a sufficient 

 structural parallelism to justify the inference that they too have 

 a visual function, it seems to me that the onus probandi lies on 

 those who maintain that the motions of insects can be thus guided 

 without sight of the objects which attract or repel them. 



In this, as in other parts of the inquiry, the answer that is 

 probably nearest the truth is that which we receive from our own 

 consciousness when rightly interrogated. It was the sagacity of 

 Hartley that first distinctly worked out the parallel (previously in 

 dicated by Descartes) between the secondary automatism which 

 man acquires by habit, and the original or primary automatism of 

 the lower animals. The act of walking, for example, though 

 originally learned by experience under the guidance of sense-im 

 pressions, comes to be so completely automatic as to be kept up 

 when once initiated by voluntary direction, not only without any 

 conscious effort, but even without any consciousness of the move 

 ments we are performing, until our attention is called to them ; so 

 that, as it is credibly asserted, soldiers fatigued by a long march 

 will continue to plod onwards (as Indian punkah-pullers will go 

 on alternately twitching and letting go their cord) in a profound 

 sleep. But whilst the locomotive actions performed in this last 

 condition resemble those of the decapitated centipede, in simply 

 carrying the body forwards without avoidance of obstacles, those 

 of a man who is awake, but whose attention is engrossed by some 

 internal object of contemplation, are obviously guided by im 

 pressions received through his visual organs. Thus I have seen 

 John S. Mill making his way along Cheapsideat its fullest afternoon 

 tide, threading his way among the foot-passengers with which its 

 narrow pavement was crowded, and neither jostling his fellows 

 n^r coming into collision with lamp-posts ; and have been assured 

 by him that his mind was then continuously engaged upon his 

 System of Logic (most of which was thought-out in his daily walks 

 between the India office and his residence at Kensington), and 

 that he had so little consciousness of what was taking place around 

 him, as not to recognize his nearest friends among the people he 

 met, until his attention had been recalled to their presence. Most 

 of us, I suppose, have had experiences of the same kind. It has 



