John Desmond Bernal (1901-1971) was undoubtedly the most important of the "Western" scientists who, during the twentieth century, accepted the Marxis… - Brian Campbell Vickery

The structure if a fully developed classification can be technically described in the following way:

Throughout life, all people are engaged in activities – practical or mental – trying to solve problems, activities that themselves give rise to problems. To solve these problems, people need knowledge. They can acquire this personal knowledge in two main ways. First, they can interrogate the world – natural and social – by means of closer observation, deeper analysis, controlled experiment, all forms of cognitive interaction. Second, they can enrich their personal knowledge by communicative interaction with the stock of public knowledge that mankind has built up over the millenia, thus acquiring what we may call information. The activities in which people engage also produce two other kinds of knowledge: that embodied in people (skills) and that embodied in their artefacts.

The basic rules of classification are - Each characteristic of division must produce at least two classes - Only one principle of division must be used at a time, to produce mutually exclusive classes. - The species of any genius must be completely exhaustive of their parent class.