What the address is to a letter, the title should be to a book; in other words, its main object should be to bring the book to those amongst the public who will take an interest in its contents. It should, therefore, be expressive; and since by its very nature it must be short, it should be concise, laconic, pregnant, and if possible give the contents in one word. A prolix title is bad; and so is one that says nothing, or is obscure and ambiguous, or even, it may be, false and misleading; this last may possibly involve the book in the same fate as overtakes a wrongly addressed letter. The worst titles of all are those which have been stolen, those, I mean, which have already been borne by other books; for they are in the first place a plagiarism, and secondly the most convincing proof of a total lack of originality in the author. A man who has not enough originality to invent a new title for his book, will be still less able to give it new contents. Akin to these stolen titles are those which have been imitated, that is to say, stolen to the extent of one half; for instance, long after I had produced my treatise On Will in Nature, Oersted wrote a book entitled On Mind in Nature.
A book can never be anything more than the impress of its author's thoughts; and the value of these will lie either in the matter about which he has thought, or in the form which his thoughts take, in other words, what it is that he has thought about it.
The matter of books is most various; and various also are the several excellences attaching to books on the score of their matter. By matter I mean everything that comes within the domain of actual experience;
