The representation of knowledge in symbolic form is a matter that has pre-occupied the world of documentation since its origin. The problem is now relevant in many situations other than documents and indexes. The structure of records and files in databases: data structures in computer programming; the syntactic and semantic structure of natural language; knowledge representation in artificial intelligence; models of human memory: in all these fields it is necessary to decide how knowledge may be represented so that the representations may be manipulated.

As cited in: Lyn Robinson and David Bawden (2011). - Concepts of documentation (1978)