Another major contribution of the 1930s is Raphael's volume (1933), comprising three studies in the sociology of art. One study, on the Marxist theory of art, sets out from a detailed analysis of Marx's text in the Grundrisse (Introduction) to construct a sociology of art. Raphael emphasizes the importance of Marx's conception of Greek mythology as the intermediary between the economic base and Greek art, and raises a series of new questions about the general relation between mythology and art. He then considers various problems connected with the "disproportionate development" of material production and art, and finally criticizes Marx's explanation of the "eternal charm" of Greek art, which he regards as "essentially incompatible with historical materialism". Raphael's own explanation of the "normative value" of Greek art in certain periods of European history is that "revivals of antiquity" occurred whenever the total culture underwent a crisis as a result of economic and social changes. In the third of these studies, Raphael analyses the art of Picasso as the most typical example of modernism and relates it to the transition from free-enterprise capitalism to monopoly capitalism.