He must decide how much of what has been told he can accept either as having actually happened, or as possible and more or less probable.

The Author must be permitted, however, to say here, in his personal character, and as responsible to the students of the human mind and body, that since this story has been in progress he has received the most startling confirmation of the possibility of the existence of a character like that which he had drawn as a purely imaginary conception in Elsie Venner.
BOSTON, January, 1861.
A SECOND PREFACE.
This is the story which a dear old lady, my very good friend, spoke of as "a medicated novel," and quite properly refused to read.

I was always pleased with her discriminating criticism.

It is a medicated novel, and if she wished to read for mere amusement and helpful recreation there was no need of troubling herself with a story written with a different end in view.
This story has called forth so many curious inquiries that it seems worth while to answer the more important questions which have occurred to its readers.
In the first place, it is not based on any well-ascertained physiological fact.

There are old fables about patients who have barked like dogs or crowed like cocks, after being bitten or wounded by those animals.