Abstract: The author traces the gradual evolution of the clinical and diagnostic category of the borderline in order to demonstrate how, in the course of a few decades, twentieth century psychiatric culture, with its own particular vision of the world, passed from an experience of limit to a concept of limit. In other words, as psychiatric culture became aware of a certain difficulty in defining an object under observation, it was gradually forced to modify its own descriptive categories and elaborate a new concept that contained within itself that primitive experience of indeterminacy. The author suggests that a similar phenomenon can also develop in other fields of human life, but here it takes place over such a long period of time that the relationship between the primitive experience and its subsequent conceptualization is difficult to trace. Through the borderline experience or the experience of limits, consciousness modifies its horizons, not in the sense of a simple integration of a new content but in the sense of a profound modification of the entire system of values in which consciousness identified itself up to that moment. It is in this key that the author attempts a psychological reading of Aeschylus’Prometheus Bound and Shakespeare's Hamlet, a reading that has also implications for the understanding of the themes emerging at present on the international scene.