Technical progress changes space and human relationships. Modern physics and psychoanalysis have emphasized the relational basis of the spaces we live in. While our day to day sensible experience places us in front of a double space, the one outside and the one inside each of us, the articulation between the two has taken a new dimension with Winnicott’s and Green’s work. Using the analysis of Theo, who experienced the analytic setting as a dangerous cavern, and the myth of Perseus, as read by Pasche, the importance of a personal shield is discussed. With its passage from a three-dimensional to a two-dimensional relationship, the mediation offered by digital technology is compared to a Perseus’ shield of a different order. Its impact is questioned at the light of developmental research and of clinical experience with adolescents.