Freud, as is well known, produced a multi-layered view of the human mind. He called psychoanalysis a ‘depth psychology’ because it examined ‘those processes in mental life which are withdrawn from consciousness’. Behind the thoughts and wishes, of which we are aware, lurks a shadowed hinterland of secret desire. It is this sense of depth that distinguishes psychoanalytic views from most other psychologies. Behaviourism posits no hidden secrets, merely chains of association and responses to outward stimuli, thereby according the human psyche all the depth of a pigeon. Cognitive psychologists envisage the human mind as an extraordinary machine, processing, storing and combining information. The average human mind is seen to be many mega-bytes more powerful than the most sophisticated computer. At worst in this model, the human information-processor is to be criticized for taking lazy short-cuts in its computation of information. At best, there is a self-admiration, because the wonders of Microsoft still paddle way behind the software of our human brains. Complexity, however, is very different from depth. The computer has no sense of shame, only multiple programs and parallel processes.

The element of depth in the Freudian vision comes from the notion that we have secrets, which we keep from ourselves. Freud put the matter simply in ‘The Question of Lay Analysis’, a short work intended for a wide audience. Freud was at pains to make the idea of unconscious ideas seem reasonable.