The intellectual development of Max Dvořák (1874-1921), one of the protagonists of the ‘Vienna School of Art History’, was characterized by a constant process of methodological self-criticism. His changing views on Medieval Art are known above all by two texts: The Enigma of the Art of the Van Eyck Brothers (1904), strongly influenced by Wickhoff and Riegl and by an ‘impressionistic’ view of modernity, and Idealism and Naturalism in Gothic Sculpture and Painting (1918), an essay dating to Dvořák’s late, ‘expressionistic’, period. Knowing only these two texts, the decisive turn undertaken by Dvořák around 1920 could be interpreted as a sudden change of paradigm. As the paper wants to show, this view has to be revised after having read and analyzed Dvořák’s hitherto unpublished university lectures on Western European Art in the Middle Ages which were given four times from 1906 to 1918.