Gesammelte Abhandlungen I - Collected Works ILike Descartes and Pascal, Hans Hahn (18791934) was both an eminent mathematician and a highly influential philosopher. He founded the Vienna Circle and was the teacher of both Kurt Gdel and Karl Popper. His seminal contributions to functional analysis and general topology had a huge impact on the development of modern analysis. Hahns passionate interest in the foundations of mathematics, vividly described in Sir Karl Poppers foreword (which became