Historian of Spanish art. Mayer's parents were Jonas Mayer and Bertha Liebmann (Mayer). His father was a merchant in Darmstadt. Mayer attended the Neues Gymnasium in Darmstadt, graduating in 1904. He studied art history, archaeolog and Germanistik at the universities at Munich and Berlin. In 1907 he received his Ph.D. from Berlin, writing a dissertation on Jusepe Ribera under Heinrich Wölfflin. He published his thesis as a book the following year.