, or you will soon find
out your mistake. Place your list of wants and your list of commissions
in the hands of one good man whom you have reason to trust, and you will
then get your money's worth.

I have said that it is impossible to set down all the causes which
affect the prices of books, but in an old French bibliographical book,
by D. Clement,[5] the subject is gone into more minutely than it has
ever since been treated. First, there are causes which may be classed
under the heading of _Rarity_. Secondly, there are causes which must be
grouped under the head _Condition_.

According to Clement, there are two sorts of rarity in books; the one
absolute, the other conditional or contingent. There are rare editions
of very common books. There are books of almost common occurrence in
public libraries, which are rarely seen in the market. A book or an
edition of which but very few copies exist is called 'necessarily rare;'
one which is only with difficulty to be met with--however many copies
may be extant--he calls 'contingently rare.'

Under the first head he classes; (1) Books of which few copies were
printed; (2) Books which have been suppressed; (3) Books which have been
almost entirely destroyed by casual fire, or other accident; (4) Books
of which a large portion of the impression has been wasted--usually for
want of success when published; (5) Volumes of which the printing was
never completed; (6) Copies on large paper or on vellum.

Under the second head, he enumerates; (1) Books on subjects which
interest only a particular class of students; (2) Books in languages
which are little known; (3) Heretical, licentious, and libellous books;
(4) First editions of a classic author from MS.; (5) First productions
of the printing press in a particular town; (6) The productions of the
celebrated printers of the sixteenth century; (7) Books in the
vernacular language of an author who printed them in a foreign country;
(8) Books privately printed; (9) Works, the various parts of which have
been published under different titles, in different sizes, or in various
places.

Clement then analyses the degrees of rarity thus: (1) Every book, which
is no longer current in the trade, and requires some pains in the search
for it, is 'of infrequent occurrence;' (2) If there are but few copies
in the country in which we live, and those not easily met with, it is
'rare;' (3) If the copies are so dispersed that there are but few of