This established, Dury proceeds to point out how the library should be made useful. His main idea is that a library should be a kind of factory, and it is astonishing how often he contrives to introduce the word "trade" into his proposals. Underlying this peculiar phraseology is the thought that so long as the library only exists for the advantage of those who may choose to resort to it, it is like a talent buried in a napkin; that to be really useful it must go to the public, and that the librarian must place himself in active communication with men of learning. It was hardly conceived in Dury's day that any but scholars could have occasion for libraries, but translating his proposals into the language of our time, it will appear that they contemplate such an ideal of librarianship as is professed in America, and is realised with no small success in many of our leading free libraries. The first condition is a good catalogue:— "That is," says Dury, "all the books and manuscripts according to the titles whereunto they belong, are to be ranked in an order most easy and obvious to be found, which I think is that of sciences and languages, when first all the books are divided into their _subjectam materiam_ whereof they treat, and then every kind of matter subdivided into their several languages." Evidently Dury was little troubled with the questions which have so exercised librarians since his time. "The subject-matter of which a book treats" is not always easy to ascertain. It might have puzzled Dury himself to decide whether his own tract should be catalogued along with books on libraries, or with the "Reformed School" to which it is professedly an appendix, and to which half its contents have a direct relation. The suggestion that books should be catalogued by languages was propounded before the British Museum Commission of 1849, and promptly dismissed as the fancy of an amateur. It would be curious to see Pope's Homer in one catalogue, Voss's in another, and the original in a third.