After having precisely defined mediation psychotherapy, the author presents the phenomenological characteristics of an encounter in general by drawing examples from literary works. He then develops his subject based on the psychological stakes of the clinical encounter with mediations. The hypothesis, at first paradoxical, is that the installment of an area of inter-relational encounter between therapist, patient, and medium would facilitate the capacity to be alone in the presence of the clinician. In reference to Winnicott, the capacity to be alone is a necessary condition for psychic elaboration in mediation psychotherapy. Finally, the author indicates a line of research in relation to the value of aesthetic emotion as a means of contact and relational experience. This is seen as a countertransferential disposition of the therapist, where s/he allows him/herself to be affected by the patient’s subconscious plastic contents.