The authors examine the transformation undergone by psychoanalytically-based theories in the context of therapeutic application and with regard to the concepts of health or mental disease, and in particular in relation to the consideration of each individuality and intersubjectivity derived from psychotherapeutic relations. The paper discusses works by some of the main supporters of this theory: W. Bion, D. Winnicott and M. Khan in the Freudian field; lastly, with regard to analytical psychology, Jung's idea of the practice of psychotherapy and his aims are fully discussed. The "hermeneutic" aspect of all psychotherapy is then emphasised and it is viewed as the intermingling and reciprocal involvement of three factors: theory, technique and interpersonal relations.