Among the many definitions of the library which do not recognize use as the library’s chief distinction, the commonest are perhaps those which adopt plurality or collection as the distinguishing factor. Many however adopt the building as chief factor. Typically, of course, the modern library does include many books, a whole separate building and a librarian, but even if the books are few, the place only a room, a chest, a bookcase, or a single shelf, and even if it is only the owner who is at the same time the keeper, it is still recognized to be a library if the books are kept for use and not for sale. Quantity does not matter: the point which divides is the matter of use or sale. Even a one book library is, in fact, a library just as much as a one cell plant is plant or a one cell animal is animal. A one book library is a very insignificant affair compared with the New York Public Library with its many books and many branches, but it is just as truly a library—or else you must find some other word. In point of fact “library” in English, or some derivative of _bibliotheca_ in most other languages, is the word which in practice stands to the book-for-use as the word animal or plant does in biology for the living thing whether it is a single cell or a cell complex. Some definitions again try to limit the library to printed books or bound books or literary works as distinguished from official or business documents, and these definitions have, as before said, sometimes led to a good deal of misunderstanding. Even if “archive” is assumed to be the right name for a collection of business documents, still such a collection is simply one kind of a library. Every one recognizes this when the collection of business documents is one of printed and bound public documents (U. S. public documents e.g.), and if the documents are tablets, rolls or folded documents, the case does not differ. If books are kept for use it makes no difference whether they are of wood, stone, metal, clay, vellum, or paper, whether they are folded documents, rolls or codexes, whether they are literary works, government or business documents: if intended for use they form a something for which some word must be found which will apply equally to all kinds of records for use and to a one-book-for-use library as well as to the New York Public Library. The right word in the English language seems to be this word “library”. The “business documents” in active current use in the registry or the counting house are perhaps the farthest away from the “library” of common speech but they are equally far from “archives” in the scientific sense, and curiously these have retained one of the very simplest and oldest names of the true library, “the books”, and of librarianship “book keeping”.