The role of formal, controlled vocabularies for indexing and retrieval is contrasted with the use of natural language for these activities. The following credo is advanced for large central information processors as appropriate to the 1970's (1) Highly structured controlled vocabularies are obsolete for indexing and retrieval; (2) The natural language of scientific prose is fully adequate for indexing and retrieval; (3) Machine-aided indexing of natural language is within the state of the art; and (4) Natural language retrieval can be conducted on-line if the request can be stated in a phrase or a sentence. (Author)