Alfred H. Barr Jr.'s Cubism and Abstract Art diagram

This diagram by Alfred Barr (Museum of Modern Art)  maps assumptions about how modern art emerged from various sources, as comprehended by a famous art critic of the time. Perhaps the diagram is more famous for what it leaves out and its assumptions than what is communicates.

"Arraying words and arrows in an art historical 2-space, Alfred Barr's famous diagram illuminated the influential exhibition Cubism and Abstract Art. Set in appropriately modern Futura type, the art chart simultaneously served as a beautiful cover for the catalog, a table of contents for the show, an organizing history of the art displayed in the museum, and a symbol of the entire enterprise. Barr, then Director of the Museum of Modern Art, imaginatively replaced the conventional typographic catalog-cover with a provocative flow chart, a didactic genealogy of interacting isms" (Edward Tufte, Beautiful Evidence, p.65). 

Illustrated in Beautiful Evidence, and the image that serves as this catalogue's cover, is Edward Tufte's revised version of Barr's diagram, adding 8 arrows that accord to Barr's 1941 unpublished manuscript on the chart in Defining Modern Art: Selected Writings of Alfred H. Barr, Jr (ed. Irving Sandler and Amy Newman, New York, 1986). ET's extensive analysis of Barr's chart shows that the chart "is an imaginative, important diagram. It also illustrated the implicit but powerful assumptions of visual summaries, and the importance of presenting evidence about the specific character and relationships among verbal elements. Many diagrammatic links and arrows assume too much and explain too little, an ambiguity in action. The more generic the arrows and lines, the greater the ambiguity" (ibid., p.68).