What is now called ‘knowledge organisation’ in this context has a long history. The simplest forms of a knowledge organisation system (KOS) are, after all, the contents list and the index of a textbook. The knowledge is in the text; the KOS is a supplementary tool that helps the reader to find his way around the text. But as such finding aids have become more complex, and taken on wider functions, they have acquired grander names, such as retrieval languages, taxonomies, categorisations, lexicons, thesauri, or ontologies. They are now seen as schemes that organize, manage, and retrieve information.

Bertie Brookes and I shared a common view that, beyond the practical activities of information provision, there could be discerned a more general science of information. He tended towards a mathematical formulation of this: I was more interested in its social aspects.

The area of scientific interest is... the study of the objectives, functions, structure, properties, behaviour, performance and effects of informative communication processes and information systems. To this study the name "information science" can legitimately be attached.

Four years ago, when the first edition of this book was written, information retrieval was beginning to crystallize out as a unified discipline. The process has gone further today. Several other books... have also offered a general survey, although each has contributed its own special emphasis. Many conferences on the subject have been held, and a constant stream of new articles has appeared, both in documentation journals and in those in the data processing field. Information retrieval is now recognized as a discipline, and further advances in theory are being made, What I described in the first edition as the key operation in retrieval — the subject description of documents — is being explored theoretically and experimentally, although we are still a long way from reducing this operation to rule (Chapter 3). There has been less new work on the design of descriptor languages, although ideas on the display of descriptor relations through thesauri and 'semantic maps' have been developed (Chapter 4). Access to files has been examined, particularly by those experienced in data processing.

Theoretical research in information science is still marked by a tendency to play safe... it is still marked by timidity. It could now afford to be more boldly speculative, intellectually exciting and therefore more attractive to intelligent and ambitious students." Have things changed?

In science there are uses many classifications of entities - plants, animals, rocks, soils, stars, diseases, occupations, and so on. In these taxonomies a classification must display genetic relations - for example, an evolutionary family tree of animal species - but its prime purpose is to aid in the identification of entities... Classification enables us to select, from the whole universe of known entities, the one that best matches one newly encountered.

We communicate with each other to inform, to instruct, to persuade, to amuse, to annoy. Informing and instructing aim to alter the receiver's concepts, whereas persuading, amusing or annoying aim to change his preferences or feelings. In a work situation people do make jokes and enemies, and use the arts of persuasion, but much of their communication has an informal or instructional aspect.

Interaction is the mode of life of living organisms. Each must feed on its environment, ingesting chemicals or other organisms. This is something more than "interaction", it is activity directed towards the environment. Since the organism must be selective in what it ingests, it needs to discriminate among the entities in its environment. From very primitive forms of discrimination, the sensory mechanisms of organisms have evolved into the senses of man, interpreted by an internal cognitive apparatus, memories of past experiences, and an ability to take rational decisions. By "rational" I mean activity that achieves intended results because it is based on a reliable understanding of the nature of the environment. In interacting with each other to carry out tasks jointly, men have further developed language, leading to a shared understanding of the environment. This shared understanding is knowledge.