THEORISING IN THE DARK 63 
comfortable circumstances in an equable temperature. 
Again, Humboldt relates that the Peruvian Indians 
distinguished between the footprints of their own 
peOple and those of whites and negroes. 
There are, besides, the aborigines of America 
from Alaska to Tierra del Fuego, the Africans, the 
Polynesians, the Malays, the inhabitants of a thou- 
sand oceanic islands, the Asiatics. I suppose that at 
least a hundred thousand Europeans have written 
books about China, Hindustan, and all the other 
countries of that vast continent, but I doubt if there 
is a chapter in the hundred thousand books dealing 
with the sense of smell in any Asiatic people compared 
with ours. 
Having, then, few or no facts to go upon, we are 
very much in the dark about this sense; we can only 
suppose that, if it be accepted as a principle that its 
decay proceeds pari passu with the increase in the 
value of vision and the improvements in our artificial 
condition of life, the decline has been greater in the 
town-dwelling and comfortably-off classes in Eng- 
land during the last two centuries than in the 
previous two thousand years. 
To dogmatise on such a subject would be ridiculous; 
we are even more in the dark than I have made it 
appear. By watching a man and subtly drawing him 
out, we can penetrate through his mask and dis- 
cover his secret and real mind, but we can't get at 
the real state of his sense of smell. Each one of us 
knows his own, and many of us only know it "in 
a way," Wherefore I'm glad to get away from this 
