REPLACING THE DEWEY DECIMAL SYSTEM WITH “BODY AND SOUL”. Jonathan Schifman also sketches the history of the Dewey Decimal System, which was devised by Melville Dewey in 1873. Each book was assigned a decimal number—a “call number”. This wikipedia entry has the groupings out to three digits—920 is biography and 822 is English drama. Strings of decimal numbers after the decimal point were used for subclassifications. You could use a card catalog to find the precise location of a book on a shelf from the numbers on the spine. Schifman says that the Ohio College Library Center distributed 1.9 billion cards for card catalogs between 1971 and 2015, at which point it stopped issuing them, thus marking the date at which online catalogs had completely replaced the card catalog.
One advantage of the Dewey Decimal System was that once you found one book which was related to the subject matter you were looking for, the system put related books on nearby shelves.
Unfortunately, after I had been happily using the Dewey Decimal System for over 50 years, one local library introduced a new system where books are grouped in large areas. A librarian helped me the first time I tried to use it. The book turned out to be located in a grouping called “Body and Soul”. I have never gone back to that library for a second attempt.