On the catalog card for a rare book.

-r'lHE primary function of any catalog card is to help people find and use a . book. The catalog card for a rare book differs from other cards only to the extent that people use rare books differently from ordinary books. When the user of a library wants, say, a mystery story or a pamphlet on the care of chickens, he is concerned only with content-with what the author has to say. He can easily discover a suitable book from a catalog containing main entries and subject headings on cards which do not give author's dates, full title, complicated pagination, or any of the thousand and one other details against which administrators are so fond of inveighing. If he cannot find the book in his own library's catalog, then an equally simple catalog card in a union catalog will locate a copy somewhere which he can borrow through interlibrary loan. Almost no one, however, wants a rare book solely for its content. This point cannot be too strongly emphasized. Content may be secured from any cheap reprint or photostat or microfilm of the book; and these reproductions, like the mystery story, can generally be obtained by consulting a brief catalog card. The rare book itself is valuable chiefly, if not entirely, as a document in the history of civilization. The discovery that a book was printed at the Pilgrim Press in Leyden, for instance, may add much to our understanding of our forebears, even though the book itself may be something we would not read on a bet. Detailed study of a rare book as a physical entity will tell much of the circumstances under which it was written and printed. What were the thought-processes of the author? How many cancels and corrections at press did he insist upon? What pressures may have been brought to bear to make him change the text? Who was the printer? Was the type set by one compositor or by several? Were there any interruptions in the printing? It is to answer these and similar questions that people use the rare book-except, of course, when they merely look at it as a curiosity in a museum showcase. The catalog card, therefore, should tell everything the cataloger has discovered about the book's significance as a historical document. Actually, locating the book is by comparison a relatively minor matter; if the card tells enough, the scholar may not even ask to see the book. This function of the catalog card for a rare book is even more evident when the card is filed in a union catalog; for, even apart from the matter of expense, it is obvious that every library cannot hope to acquire a copy of every rare book. Even if it could, there would be no assurance that upon examination its "copy" would not turn out to be a "variant issue" or even a different edition instead of a "copy." Yet the full significance of any rare book becomes apparent only when its relationship with other editions and issues of its text, and often with other books, is understood. If two editions of a book, both published in, say, I58o, differ chiefly in that the collation of one is "A-B4, *B4, C-D4" and of the other, simply "A-E4," it is probable that the second is the later edition. And what is