 Müller went to school in Halle for eight years, after which his father expected him to start an apprenticeship as an electrician.He was rejected however on account of his small stature and went on instead to train as a lithographer from 1913 to 1917.During this period, he also attended evening classes in drawing and painting at the Staatliche Städtische Handwerkerschule, later known as the Kunstgewerbeschule Burg Giebichenstein (Burg Giebichstein Academy of Arts and Crafts, in Halle.