For more than ten years, psychiatrist and advocate of "dasein-analysis" Medard Boss organized seminars in Zollikon, Switzerland, in which philosopher Martin Heidegger analyzed the ontological foundation of psychiatry and psychotherapy. According to the philosopher, psychiatry and psychotherapy are based on inappropriate ontological foundations, which they adopt uncritically through the application of the natural scientific method to phenomena of the human psyche. The search for appropriate ontological foundations and methodological tools requires a genuine phenomenological approach.

These issues are examined by the philosopher not only in the seminars themselves (Part A, ed. Flows, 2015), but also in private conversations with Boss and in his letters to him. He offers enlightening explanations and additions to what is discussed in the seminars. In fact, in this personal communication with Boss, he confronts questions that concern specific issues in psychiatry and psychotherapy. He directly expresses himself on topics such as projection and introjection, dreams and their interpretation, Freudian psychic components "Id, Ego, and Superego," and more.

With the conversations and letters, the Greek edition of the so-called Zollikon Seminars is completed. The texts included in them hold a special place in Heidegger's work. They are his only texts that thoroughly address the philosophical foundation of a science and express his critique of modern science and its objectification. They also provide access to his reflection for interested individuals without specialized philosophical knowledge, as the philosopher, in conversing here with non-experts, uses a much simpler and more accessible language than in his other texts.