In the Library of the British Museum the classification starts with Theology, followed by 2. Jurisprudence; 3. Natural History (including Botany, Geology, Zooelogy, and Medicine); 4. Art (including Archaeology, Fine Arts, Architecture, Music, and Useful Arts); 5. Philosophy (including Politics, Economics, Sociology, Education, Ethics, Metaphysics, Mathematics, Military and Naval Science, and Chemistry); 6. History (including Heraldry and Genealogy); 7. Geography (including Ethnology); 8. Biography (including Epistles); 9. Belles-lettres (including Poetry, Drama, Rhetoric, Criticism, Bibliography, Collected Works, Encyclopaedias, Speeches, Proverbs, Anecdotes, Satirical and facetious works, Essays, Folklore and Fiction); 10. Philology. Sub-divisions by countries are introduced in nearly all the classes. In the Library of Congress the classification was originally based upon Lord Bacon's scheme for the division of knowledge into three great classes, according to the faculty of the mind employed in each. 1. History (based upon memory); 2. Philosophy (based upon reason); 3. Poetry (based upon imagination). This scheme was much better adapted to a classification of ideas than of books. Its failure to answer the ends of a practical classification of the library led to radical modifications of the plan, as applied to the books on the shelves, for reasons of logical arrangement, as well as of convenience. A more thorough and systematic re-arrangement is now in progress. Mr. C. A. Cutter has devised a system of "Expansive classification," now widely used in American libraries. In this, the classes are each indicated by a single letter, followed by numbers representing divisions by countries, and these in turn by letters indicating sub-divisions by subjects, etc. It is claimed that this method is not a rigid unchangeable system, but adaptable in a high degree, and capable of modification to suit the special wants of any library. In it the whole range of literature and science is divided into several grand classes, which, with their sub-classes, are indicated by the twenty-six letters of the alphabet. Thus Class A embraces Generalia; B to D, Spiritual sciences (including philosophy and religion); E to G, Historical sciences (including, besides history and biography, geography and travels); H to K, Social sciences (including law and political science and economics); L to P, Natural sciences; Q, Medicine; and R to Z, Arts (including not only mechanical, recreative and fine arts, but music, languages, literature, and bibliography). The sub-divisions of these principal classes are arranged with progressive fullness, to suit smaller or larger libraries. Thus, the first classification provides only eleven classes, suited to very small libraries: the second is expanded to fifteen classes, the third to thirty classes, and so on up to the seventh or final one, designed to provide for the arrangement of the very largest libraries.