The study of the structure and development of the UoS by the information professional can be shown to be a necessary implication of the five laws of library science.

Law 1 And Its Implications

The first law is "Books are for use". Here, the term "book" is a generic term to denote all kinds of documents, including books themselves, periodicals, technical reports, patents, specifications, non-conventional and meta-documents. The document, in its turn, is a trinity of
i) Soul - embodied knowledge;

ii) Subtle body - language and expression of the knowledge; and

iii) Gross body - physical body of the document.

The term "use", on the other hand, implies essentially the use of organised, expressed and embodied knowledge - that is, the subject dealt with in documents - by the readers, although the subtle body is indispensable for the acquisition of knowledge and as a vehicle `for its communication, and the physical body is a convenient means of transport of the embodied knowledge across space and through time. A document retrieval system is, therefore, essentially concerned with the classification, search, retrieval, and service of the "subject".

A subject, in. its turn, is an organised or systematised body of ideas, whose extension and intension are likely to fall coherently within the field of interest and comfortably within the intellectual competence of and the field of inevitable specialisation of a normal person.