The Swiss color scientist and practitioner Aemilius Müller (1901-1989) published numerous color atlases, color plates, and writings on color theory. He operated the Chromos publishing house as a one-man business in Winterthur. His books and teaching materials on color science achieved print runs in the four-digit range; they are not only of interest to professionals but are also aesthetically very appealing. In the scientific community, Aemilius Müller is particularly known for his further development of Wilhelm Ostwald's color theory. The color expert Werner Spillmann acquired Aemilius Müller's color works during Müller's lifetime and initiated exhibitions in Winterthur, Frankfurt a. M., New York, and other locations. In this richly illustrated volume, he provides an overview of Müller's extensive oeuvre, with a focus on the impressive late works.