It appears, therefore, that, although great books unquestionably demand more intellectual power for their production than great works of art, their very superiority tends to cheapen them in comparison by encouraging their dissemination. There could not be a stronger instance of the power of scarcity in determining price; and, in fact, the rarity of a book is the most important element in its commercial worth. Yet intrinsic desert plays its part, though an inferior one. There are some cases in which it utterly fails. The commercial value of the productions of the Dutch prototypographers, for example, would probably not be augmented in the least if they could be transformed from fragments of dull lesson-books into leaves from sages and poets. The Papal Bulls relating to the Turks in Cyprus, which have the honour to be the first documents to have issued complete from an European press, would hardly gain in commercial value if they were briefs announcing the foundation of the Vatican Library, or official announcements of the fall of Constantinople. On the other hand, the first edition of Virgil, one of the rarest of books, would assuredly be less valued if, while equally rare, it were the _editio princeps_ of a Latin author of inferior reputation. In general, the celebrity of an author will be found a considerable factor in determining the value of a book; but while rarity without celebrity will effect much, celebrity without rarity, or some other adventitious circumstance devoid of relation to the intellectual value of the book, will effect very little.