Private scholar; art historian of the baroque and modern periods; methodological theorist. Badt was born to a prosperous Banking family in Berlin. His father, Leopold Badt (1858-1929) raised his children in a rarefied cultural atmosphere, giving them every opportunity to experience art. The younger Badt attended the Berlin-Charlottenburg Reformgymnasium, graduating in 1906. Between 1909-1914 he studied art history and philosophy at the universities of Berlin, Munich and finally at Freiburg (im Breisgau) under Wilhelm Vöge.

Hetzer studied art history under Wilhelm Vöge and Heinrich Wölfflin. However, it was at Basel that the teaching of Friedrich Rintelen greatly affected his work, particularly his appreciation for Giotto. He wrote his dissertation under Rintelen on the early paintings of Titian with a degree granted in 1919. Hetzer was appointed professor of art history at the University of Leipzig in 1923, focusing on the art of the Italian and northern Renaissance, Giotto, Titian and Raphael, and Dürer.

Art critic and early German historian of modern art. He was born in Eppendorf, Germany, which is present-day Hamburg, Germany. Scheffler graduated from the Realschule and took over his father's interior painting business. In 1888 he attended the Kunstgewerbeschule of Berlin where he mastered tapestry design. After working for a Berlin fabric firm, he started to write articles for the magazines Atelier and the Dekorative Kunst in 1897, and after 1899 for the better known Die Zukunft.