at subject, as to take up most of the copies
in market, and enhance the price of the remainder. Thus, Napoleon's
conquering career in Egypt created a great demand for all books on Egypt
and Africa. The scheme for founding a great French colony in Louisiana
raised the price of all books and pamphlets on that region, which soon
after fell into the possession of the United States. President Lincoln's
assassination caused a demand for all accounts of the murder of the heads
of nations. Latterly, all books on Cuba, the West Indies, and the
Philippines have been in unprecedented demand, and dealers have raised
the prices, which will again decline after the recent public interest in
them has been supplanted by future events.

There is a broad distinction to be drawn between books which are
absolutely rare, and those which are only relatively scarce, or which
become temporarily rare, as just explained. Thus, a large share of the
books published in the infancy of printing are _rare_; nearly all which
appeared in the quarter century after printing began are _very_ rare; and
several among these last are _superlatively_ rare. I may instance the
Mazarin Bible of Gutenberg and Schoeffer (1455?) of which only
twenty-four copies are known, nearly all in public libraries, where they
ought to be; the Mentz Psalter of the same printers, 1457, the first book
ever printed with a date; and the first edition of Livy, Rome [1469] the
only copy of which printed on vellum is in the British Museum Library.

One reason of the scarcity of books emanating from the presses of the
fifteenth century is that of many of them the editions consisted of only
two hundred to three hundred copies, of which the large number absorbed
in public libraries, or destroyed by use, fire or decay, left very few in
the hands of booksellers or private persons. Still, it is a great mistake
to infer that all books printed before A. D. 1500 are rare. The editions
of many were large, especially after about 1480, many were reprinted in
several editions, and of such incunabula copies can even now be picked up
on the continent at very low prices.

Contrary to a wide-spread belief, mere age adds very little to the value
of any book, and oft-times nothing at all. All librarians are pestered
to buy "hundred year old" treatises on theology or philosophy, as dry as
the desert of Sahara, on the ground that they are both old and rare,
whereas such books, two hundred and even three hun