- This article, inspired by the writings of the philosopher Hannah Arendt, presents the concept of ‘Public Space' and traces its origins to the practice in the Polis (City State) of ancient Athens. The author points out that Public Space is a genuinely human domain, different from goal-oriented, reproductive activities shared with animals. He underlines the importance of distinguishing public from private space. Humans live in both, neither can exist without the other, but as a rule they must be kept separate and differentiated. The author attributes to public space the freedom of diversity and expression without loyalties, to see and to be seen and to act spontaneously in cooperation with others. He recruits Hanna Arendt, Sigmund Freud and J. L. Moreno in an appeal against a rising trend to conformity and ‘recognised' methods in psychotherapeutic practice and puts forward the idea of psychotherapy as an exchange, a public space, between two or more persons with a focus on the encounter between them. These qualities are most easily reached in group psychotherapy and in psychodrama, where spontaneity is the desired instrument.