The purpose of this paper is to introduce a new method of information retrieval by man-machine interaction. The dialogue supported has more symmetry than most interactive computer systems in that the machine forms an image (rather as a man does) of the view of the human enquirer, without requiring him to ask a precise question, and responds with references according to its image. Initial tests with a prototype program indicate that a performance equal to that obtainable from a more conventional on-line retrieval system is possible without obliging the user to formulate his query.