It is a fact, though a paradoxical one, that psychoanalysts tend to consider illusion as a psychic category and to refer to it in a specific way. This chapter presents a detailed case report from a French analyst of a patient who could be seen as having lived out a mirroring illusion in his relationship with his mother and then in the transference. At a certain point in the analysis, a point unconsciously pre-determined by the patient, an exchange occurred between patient and analyst that totally shifted the atmosphere of the analysis and the patient’s way of being. It is also a moment that illustrates the phenomenon of sudden change in analysis, as evidenced by a major shift in the patient’s psychic position, especially in his relationship to desire. It is a Lacanian truism that Oedipus never went through the Oedipus complex.