Quality in art is not just a matter of private experience. There is a consensus of taste.
Important works of art embody important innovations. The most important works of art are those that announce very important innovations.
There is considerable interest in identifying the most important artists, and their most important works, not only among those who study art professionally, but also among a wider public. The distinguished art historian Meyer Schapiro recognized that this is due in large part to the market value of works of art: “The great interest in painting and sculpture (versus poetry) arises precisely from its unique character as art that produces expensive, rare, and speculative commodities.” Schapiro's insight suggests one means of identifying the most important artists, through analysis of prices at public sales. This strategy is less useful in identifying the most important individual works of art, however, for these rarely, if ever, come to market.
An alternative is to survey the judgments of art experts. One way to do this is by analyzing textbooks. The illustrations an author chooses implicitly tell us which works of art he considers most valuable in providing a narrative of the successive innovations that make up the history of art. Surveying a large number of textbooks effectively allows us to poll art historians as to which works are generally considered the most essential to this narrative.