As mentioned earlier, the Dewey Decimal System is able to classify all knowledge. Even the impossible. The Library
of Congress System, on the other hand, only classifies known knowledge. I realize that this sounds like Donald Rumsfeld discussing “known unknowns,” but it means that a number doesn’t exist until something is written about it.
To use the example given in the previous post, there will never be an LC number for Martian Polar Bears, because it is impossible to write a non-fiction book about the subject.
The LC Classes are, unsurprisingly, based on the collection at the Library of Congress. After the War of 1812, Thomas Jefferson donated his personal collection to replace the one that had been burned by British troops. This accounts for the fact that ENTIRE CLASSES are devoted to Naval and Military Science.
The main classes of LC are:
A General Works
B Philosophy, Psychology, and Religion
C Auxiliary Sciences of History
D General and Old World History
E History of America
F History of the United States and British, Dutch, French, and Latin America
G Geography, Anthropology, and Recreation
H Social Sciences
J Political Science
N Fine Arts
P Language and Literature
U Military Science
V Naval Science
Z Bibliography, Library Science, and General Information Resources
It should come as no surprise that we have started packing LC J-Z. The LC B’s will be packed last.
The following sections are now boxed (newest in bold):
Dewey Decimal 200-259
Library of Congress J-Z
4th Floor Periodicals (to 1989) PER A-Z
Dewey Decimal Size 2 and Size 3 (+ and //)
Library of Congress Size 2 and Size 3
Dewey Decimal 000-199
Dewey Decimal 300-999