In 1652 he entered the service of the duke of Saxe-Gotha, in which he continued until 1678, when he retired to Frankfurt am Main. In 1683 he visited England to promote a cherished scheme for establishing trade with Ethiopia, but his efforts were unsuccessful, chiefly due to the resistance of the authorities of the Ethiopian Orthodox Church. Returning to Frankfurt in 1684, he devoted himself wholly to literary work, which he continued almost to his death. In 1690 he was appointed president of the Collegium Imperiale Historicum.