I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection, in order to mark its relation to man's power of selection. But the expression often used by Mr. Herbert Spencer of the Survival of the Fittest is more accurate, and is sometimes equally convenient.
Men who no longer can make sure of the reality which they feel and experience through talking about it and sharing it with their fellow-men, live in the same nightmare of loneliness and uncertainty which, in a normal world, is the terrible fate of insanity.