Let's start by looking at some simple numbers. For the purposes of this chapter I have chosen some real books whose titles adequately express their subject-matter. In real life, of course, you do not classify something just by looking at its title, and so to some extent this is all slightly artificial, but it is the best we can do in a textbook.

How do you go about finding a number for something that you have to classify? There are two main processes in practical classification:

We shall start with some simple subjects which do not require numberbuilding. There are basically two ways of finding numbers:

You will find that many people take the view that you ought to adopt the first method whenever possible, because this is the only way to be sure that you class the item in the right discipline (and remember that Dewey is a discipline-based scheme). However, if you do this all the time, especially when you are a beginner, you will waste quite a lot of time and still not necessarily get to the right place.

It really is a very good idea to use the index; that's what it's there for. Melvil Dewey planned it as an integral part of the scheme right from the start, particularly because this is an aspect-based scheme. It is called a relative index because it relates the subjects to the various disciplines to which they may belong. It is a waste if you do not use it.