ODORS AND LIFE. 201 



a bath of juice of strawberries and raspberries, used to be 

 gently rubbed with sponges saturated with perfumed milk. 

 Napoleon I. every morning poured eau-de-Cologne, with 

 his own hands, over his head and shoulders. 



IV. 



Above all these questions which we have just skimmed, 

 there rises another, of a graver and more mysterious kind, 

 one which occurs at the end of all studies that treat of 

 sensation, and with regard to which some reflections will 

 not be out of place here. To what, outside of us, do those 

 sensations which we experience within us correspond? 

 What relation is there between the real world and that im- 

 age of the world shadowed in our soul ? In the special case 

 we are concerned with, what is it in these substances which 

 is the cause why they affect our sense of smell ? It seems 

 certain, in the first place, that odor in itself, so far as it is 

 odor, is a mere figment of our mind. Contemporaneous 

 physiology proves that excitement of the nerves of sensa- 

 tion is followed, in each one, by the sensation that corre- 

 sponds with each. When we electrify the eye, we call up 

 in it an appearance of light ; when we electrify the tongue, 

 we produce in it a sensation of taste ; when we electrify 

 the inside of the ear, we provoke in it the effect of a sound. 

 So, too, a similar excitement, electric or otherwise, of the 

 olfactory nerves, creates in our mind the sensation of smell, 

 even though no odorous molecule takes part in the phenom- 

 enon. Sensation, therefore, seems to depend chiefly on 

 the nature of the sensitive nerve. The external world 

 seems to contribute to it only by setting in motion the 

 nerve-fibres. Even this condition of an impulse infringing 

 from without is not andispensable, since in sleep, and in 

 madness, we experience sensations of smell which, by the 

 testimony of our other senses, answer to no external agent. 

 Still, we believe that we can distinguish cases of hallucina- 



