plessner submitted his habilitation, the extra post-doctoral qualification needed to lecture at a german university, to the faculty at the university of giessen. he was denied because he happened to be a russian citizen. he then moved to moscow and joined the research group of nikolai nikolaevich luzin at moscow state university. though he left germany before the nazi's seized power in 1933, some scholars consider him an early jewish emigrant from nazi germany; his career was negatively impacted by anti-semitism and he was not able to return to germany, unlike early non-jewish emigrants such as eberhard hopf and wilhelm maier. one scholar writes that in plessner's case "the anti-semitic prejudice was mixed with and partly hidden by concern for their lack of a german citizenship".