The Dewey Subjects


Dewey thought about all the knowledge in the world. How could he divide that knowledge? He decided on ten main classes and gave each a multiple of 100:

000 General Knowledge

100 Philosophy and Psychology

200 Religion

300 Social Sciences

400 Languages

500 Science

600 Technology

700 The Arts

800 Literature

900 Geography and History

Mr. Dewey then divided each class into ten more divisions. Here are the divisions for Science:

500 General Science

510 Mathematics

520 Astronomy

530 Physics

540 Chemistry

550 Earth Sciences

560 Paleontology

570 Life Sciences

580 Botany

590 Zoology

Each of these subjects are also divided into smaller divisions. Here are a few in 590:

597 Fish

598 Birds

599 Mammals

Each of these are also didvided after adding a decimal point. Here are a few from 599:

599.7 Carnivores

599.8 Primates

599.9 Humans

All Dewey Decimal numbers have three whole number digits, including those below 100:

031 is encyclopedias

There may or may not be more digits after a decimal point.There may be many :


Find out more about call numbers here.

Two quotes from Mr. Dewey:

"Thus all the books on any given subject are found standing together, and no additions or changes ever separate them."

Melvile Dewey, 1876

In our digital world, Mr. Dewey's (1851-1931) thoughts are just as important today as they were in 1876 when he invented a way to arrange the books. Learning about how information is organized will help you find the information you need both in print or on the computer.

Understanding how Mr. Dewey arranged topics in a heirarchy will help you become a better searcher in the digital world.You will learn how topics are related to one another so you can change or modify your search to better find the information you need.


Heirarchy: an arrangement of topics according to their relationship to each other; in our case, from biggest (General Knowledge) to smallest (Mammals -- on this chart)

Here is a small part:


"Not only are all the books on the subject sought, found together, but the most nearly allied subjects precede and follow, they in turn being preceded and followed by other allied subjects as far as practicable." Melvile Dewey, 1876


What Dewey is saying here is that not only are all the books about the same topic grouped together on the shelf, but also that topics related to that group of books are also located near each other: so Reptiles will be near Mammals, not near World War II.



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