Medard Boss attended the Zollikon Seminars, a series of seminars given by Martin Heidegger in 1959 and 1960. During these seminars, Heidegger discussed his later work, which focused on the role of language and the "clearing" (Lichtung) in the disclosure of Being. Heidegger's later work was characterized by a more historical and poetic approach, which emphasized the importance of language and culture in shaping our understanding of the world.
While it is possible that Heidegger may have touched on some of his earlier ideas during the Zollikon Seminars, the primary focus of his discussions was on his later work. Medard Boss, as a participant in these seminars, would have learned primarily from Heidegger's later ideas, which were the focus of his discussions.
It is worth noting, however, that Heidegger's later work was not a complete break from his earlier ideas. Rather, it represented a shift in emphasis and approach, as Heidegger sought to develop a more comprehensive understanding of the question of Being. So while Medard Boss would have primarily learned from Heidegger's later work during the Zollikon Seminars, he would also have been exposed to some of the key ideas from Heidegger's earlier work, which laid the foundation for his later thought.
