"Lernen," which in German means to study, but which, according to Rosenzweig in a 1919 letter to Margrit Rosenstock, in a Jewish context means both to study and to teach, is possible wherever people come together and try to overcome their estrangement from Judaism.The Lehrhaus in Frankfurt was not dependent on rabbis or religious teachers, but on people who knew little, in Rosenzweig's words: "am ha-arets" (without Jewish education), but who brought with them a great enthusiasm in their return to Judaism.His father Georg financially supported many charity institutions, including the Jewish community, but the family's adherence to Judaism was minimal.
Cohen was of enormous importance for the young returning Jew, who saw in his teacher a great philosopher and someone who represented a source of Jewish tradition.
Only in 1916 did Rosenzweig resume his lengthy theological correspondence with Rosenstock, after he had strengthened his renewed Jewish roots; in this correspondence with his friend he explained his new existential position.
After a few days he wrote his friends, "I shall remain a Jew." He then reshaped his life, rethought his identity, and devoted his further life to a sincere return to Judaism, moving from the periphery of Jewish life to its center.
He developed a very close relationship with the philosopher Hermann *Cohen, who had retired from the University of Marburg and now taught at the Hochschule fuer die Wissenschaft des Judentums, the institution for adult Jewish education in Berlin.
The teachers were Jews on the periphery who were assimilated and wanted to rediscover their identity.
People would be willing to read Jewish texts, such as the Bible, Midrash, Talmud, the siddur or maḥzor, and discover and build a Jewish life.In the Lehrhaus, he used his talents not to write books, but to provide living answers to questions from the public, who were increasingly interested after the war in the return to Jewish faith.According to Rosenzweig, the uniqueness of the Lehrhaus was in that people took part in conversations through questions and counter-questions.New light has now been shed on it by Rosenzweig's correspondence with Gritli Rosenstock, which will be discussed below.The Star of Redemption was written from August 23, 1918, to February 16, 1919, and published in 1921.Although he disliked Rosenstock's continued attempts to convert him, the two remained in close contact.Rosenzweig inherited from his friend the idea of revelation as "orientation" in life, and devoted his first Jewish theological essay (Atheistische Theologie) to the idea of revelation, which went beyond what Rosenstock wrote and debated with Buber.After months of deep conversations, and especially the catastrophic conversation with Rosenstock during the night of July 7, 1913, Rosenzweig decided to convert.But he then made the condition, to convert not "as a pagan," but "as a Jew." All this led to a crisis and almost to suicide.In his return to Judaism, Rosenzweig was supported primarily by Hermann Cohen, but also by people such as Rabbi Nehemiah Nobel, Martin Buber, Joseph Prager, and Eduard Strauss.In 1920 he married Edith Hahn, and progressively observed the Jewish laws. Realizing that, as a returnee to Judaism, he could play a pivotal role in bringing Jews back to their roots, Rosenzweig became interested in Jewish education, and in 1920 was appointed director of the Freies Juedisches Lehrhaus, an institute of adult Jewish education in Frankfurt on the Main, in which the participants were invited to express their view on Jewish problems and to try to understand their identity.