Herman Müntz, a well known mathematician of Polish-Jewish origin, was born in 1884 and completed his doctorate in Berlin. Besides mathematics, he had an active interest in philosophy, Jewish culture, painting, and politics. After a spell as a teacher at Paul Geheeb's progressive Odenwaldschule, he became an assistant to Albert Einstein in Berlin in the late 1920s. At the end of his assignment, difficulties in getting an academic position in Germany led him to accept an invitation form Russia, where he occupied leading academic positions and represented this country at international scientific meetings abroad. In 1938 he had to leave Russia and moved to Sweden, where he died in 1956. In this lecture, selected letters from his correspondence (with interesting insights on the political and academic life in Germany between the two World Wars, as well as on Jewish matters and emigration) to and from Einstein, Martin Buber and other leading personalities will be put into context and discussed.