The first step in analyzing any scheme must be to discover how it deals with the fundamental forms of knowledge. At first sight DC apears to use the fundamental forms as its basis: philosophy, natural science, technology, social science, history, religion and art all appear as main classes, Only 400 seems to be out of place, containing linguistics, a social science, and prescriptive usage, which bdongs among the instruments of knowledge. Social practice, moral knowledge, criticism and personal experience do not feature as main classes, though most people would probably assume, correctly, that the first three are merged with social science, philosophy and the arts respectively. However, there is a big difference between appearance and reality in all of the general schemes. The implication of titles such as ‘philosophy’, ‘religion’, ‘science’ and ‘history’ is that such classes contain all of and nothing but the subject concerned. In fact, this is far from being true since the attempt to arrange subjects helpfully for users considerably alters the apparent plan. In particular, anyone assuming that all of philosophy or all of history were to be found 1 in classes 100 and 900 respectively would be badly astray: much of these two subjects is to be found elsewhere in the scheme.