Editing Martin Heidegger (section)

===Marburg===
In 1923, Heidegger was elected to an [[Professor#Main positions 2|extraordinary professorship]] in philosophy at the [[University of Marburg]]. His colleagues there included [[Rudolf Bultmann]], [[Nicolai Hartmann]], [[Paul Tillich]], and [[Paul Natorp]].{{sfn|Gross|Kemmann|2005|page=65}} Heidegger's students at Marburg included [[Hans-Georg Gadamer]], [[Hannah Arendt]], [[Karl Löwith]], [[Gerhard Krüger (philosopher)|Gerhard Krüger]], [[Leo Strauss]], [[Jacob Klein (philosopher)|Jacob Klein]], [[Günther Anders]], and [[Hans Jonas]]. Following [[Aristotle]], he began to develop in his lectures the main theme of his philosophy: the question of the sense of being. He extended the concept of subject to the dimension of history and concrete [[existence]], which he found prefigured in such Christian thinkers as [[Paul of Tarsus]], [[Augustine of Hippo]], [[Martin Luther]], and [[Søren Kierkegaard]]. He also read the works of [[Wilhelm Dilthey]], Husserl, [[Max Scheler]], and [[Friedrich Nietzsche]].{{sfn|Wheeler|2020|loc=§1}}

In 1925, a 35-year-old Heidegger began what would be a four-year affair with Hannah Arendt, who was then 19 years old and his student. Like Blochmann, Arendt was Jewish. Heidegger and Arendt agreed to keep the details of the relationship a secret, preserving their letters, but keeping them unavailable.{{sfn|Young-Bruehl|2004|p=50}}<ref>{{Cite web|url=https://www.themarginalian.org/2016/04/25/hannah-arendt-martin-heidegger-love-letters/|title=The Remarkable Love Letters of Hannah Arendt and Martin Heidegger|first=Maria|last=Popova|date=25 April 2016|access-date=24 January 2024|archive-date=24 January 2024|archive-url=https://web.archive.org/web/20240124183352/https://www.themarginalian.org/2016/04/25/hannah-arendt-martin-heidegger-love-letters/|url-status=live}}</ref> The affair was not widely known until 1995, when [[Elzbieta Ettinger]] gained access to the sealed correspondence. Nevertheless, Arendt faced criticism for her association with Heidegger after his election as [[Rector (academia)|rector]] at the University of Freiburg in 1933.

In 1927, Heidegger published his main work, ''[[Being and Time|Sein und Zeit]]'' (''Being and Time''). He was primarily concerned to qualify to be a full professor.{{sfn|Inwood|2019|loc=chapter 1}} The book, however, did more than this: it raised him to "a position of international intellectual visibility."{{sfn|Wheeler|2020|loc=§1}}