Abstract

During the twentieth century, bibliographic classification theory underwent a structural revolution. The first modern bibliographic classifications were top-down systems that started at the universe of knowledge and subdivided that universe downward to minute subclasses. After the invention of faceted classification by S.R. Ranganathan, the ideal was to build bottom-up classifications that started with the universe of concepts and built upward to larger and larger faceted classes. This ideal has not been achieved, and the two kinds of classification systems are not mutually exclusive. This paper examines the process by which this structural revolution was accomplished by looking at the spread of facet theory after 1924 when Ranganathan attended the School of Librarianship, London, through selected classification textbooks that were published after that date. To this end, the paper examines the role of W.C.B. Sayers as a teacher and author of three editions of The Manual of Classification for Librarians and Bibliographers. Sayers influenced both Ranganathan and the various members of the Classification Research Group (CRG) who were his students. Further, the paper contrasts the methods of evaluating classification systems that arose between Sayers’s Canons of Classification in 1915–1916 and J. Mills’s A Modern Outline of Library Classification in 1960 in order to demonstrate the speed with which one kind of classificatory structure was overtaken by another.