Towards a Psychological Economy of the Book
It has been said of money that it is a commodity like any other, which is already a great mistake. But, were one to say that books are commodities like others, one would be making a far graver mistake. To class books among riches is to confuse what pertains to intelligence with what pertains to need or will. The value of a book is an ambiguous expression, because each of its copies, to the extent that it is tangible, appropriable, exchangeable and consumable has a venal value which expresses its degree of desirability, but, in itself, as essentially intelligible, inappropriable, unexchangeable, and inconsumable, which does not mean indestructible, it possesses a scientific value, which expresses its degree of credibility, without counting its literary value, which signifies its degree of expressive seduction. But, whether considered as product or as teaching, a book is capable of allying itself with other books or of combating them. There is no book, considered as a teaching, which is not made with other books, often given in the bibliography, and among which there are some of which one can say that it is made for them, because it confirms and completes them. Moreover, there is also no book which is not made against other books.
Gabriel Tarde, Psychologie économique, Tome I, Paris, F. Alcan, 1902