There is no difference in fact between patient and future psychoanalyst. Didactic psychoanalysis, applied on the future psychoanalyst, is almost the same thing as therapeutic psychoanalysis - applied to some neurotic person.

Why this identity? First of all, as all people are neurotic to a certain extent, future psychoanalysts need to be examined as patients too, so they can be cured of their own neuroses.

Secondly, the candidate in psychoanalysis is absolutely compelled to learn how to run a dialogue with  his or her own unconscious. And that "dialogue" starts in the mastery to discover the presence of unconscious, by using the main techniques for psychic investigation that psychoanalysis mainly uses.

Why the need to acknowledge unconscious? With neurotic patients, acknowledging repressed(1) drives most often end in healing. With future psychoanalysts, besides the advantage of their own restoration, they still need the ability to acknowledge the unconscious of future patients and that is impossible unless the analyst has acknowledged his/her own psyche.

At the same time, when confronted with their patients, future psychoanalysts have to be able to acknowledge their own counter-transference. That is crucial if we mean not to have some negative, emotional, interference with the development of the therapy.

Thirdly, candidates will check on the validity of psychoanalytic (Freudian) theories only after they have practiced working with their own unconscious.

There is no one able to confirm psychoanalytic theories unless they have somehow tested these on themselves.