In November 2017 a damaged and heavily restored painting of Christ, attributed to Leonardo da Vinci and called Salvator Mundi, sold at auction in New York for about 450 million dollars, the highest price ever paid for a painting. In 2005 it had been bought for little more than a thousand dollars as the work of a follower. Some experts still doubt that Leonardo painted much of it. The Salvator Mundi sale shows that a work's price depends heavily on its attribution, which experts can dispute. Behind every famous object stand people and institutions deciding what it is, what it is worth and where it belongs.

The public museum

For most of history the finest art was owned by churches, rulers and the rich, and seen by few. The French Revolution changed that. In 1793 the revolutionary government opened the former royal collection in the Louvre to the public, presenting art as the shared heritage of citizens rather than the property of kings. Public museums spread through Europe and the Americas in the following century, and with them a new power: deciding which works hang on the walls, in what order and with what labels.

A museum's choices create a canon, a list of works and artists treated as essential. Canons are useful; they give students a common starting point. But they also leave people out. For centuries art history textbooks contained few women and few artists from outside Europe and North America.

Who was left out, and why

In 1971 the American art historian Linda Nochlin published an essay asking why history recorded so few celebrated women artists. Her answer was not that women lacked talent. Nochlin argued that institutions, such as exclusion from academies and from drawing the nude, kept women from becoming celebrated artists, since training in the human figure was the gateway to history painting and the highest honors. The question was about the system, not about individuals.

Some women overcame these barriers. The Italian painter Artemisia Gentileschi, working in the early seventeenth century, painted powerful scenes of biblical heroines such as Judith. In 1616 Artemisia Gentileschi became the first woman admitted to Florence's Academy of the Arts of Drawing. Since 1985 an anonymous group of artists called the Guerrilla Girls has used posters and statistics to show how few women and artists of color are represented in major museums.

Whose property? Repatriation

Many museum objects arrived through war and conquest. Provenance is the documented history of a work's ownership, and gaps in provenance can hide theft. During the Nazi era thousands of works were seized from Jewish owners or sold under duress. The Washington Principles of 1998 committed dozens of governments to identify art looted by the Nazis and seek fair solutions with the heirs, and many works have since been returned.

Colonial collecting raises similar questions. In 2018 a report commissioned by President Emmanuel Macron, written by the scholars Felwine Sarr and Bénédicte Savoy, recommended returning African objects taken without consent. Among the best known are the Benin Bronzes, seized when a British punitive expedition attacked Benin City in 1897. Some museums argue that global collections let millions of people see world cultures side by side, and that some objects were legally bought or are better protected where they are. Critics answer that legal title gained by force is not a fair claim, and that source communities have a right to their own heritage. Debates over the Parthenon sculptures in London follow the same lines.

Who says it is art at all?

Duchamp's readymades, met earlier, left philosophers with a puzzle. In 1964 Andy Warhol exhibited wooden boxes printed to look exactly like supermarket cartons of Brillo soap pads. If they look identical to the real cartons, what makes one art? The philosopher Arthur Danto argued that the difference lies in a surrounding world of theory and history. George Dickie developed a related institutional theory: something is art when the institutions of the art world, such as galleries, museums and critics, present it as art. Critics reply that this makes art circular and leaves no room for judging quality, and that many traditions in this course made great art with no art world in the modern sense.

Worked example: a brass plaque from Benin

Picture a rectangular brass plaque, about half a meter tall, in a European museum. Form: in high relief, a king of Benin, the Oba, stands at the center, larger than the attendants who support his arms, a clear use of hierarchical scale. The metal is cast by the lost-wax method with great precision.

Content: plaques like this once covered the wooden pillars of the royal palace in Benin City, in present-day Nigeria, and served as a visual record of court ceremony and history. They were made by a royal guild of casters from about the sixteenth century onward.

Context and provenance: in the 1897 attack, soldiers took thousands of objects, and many were sold to pay for the expedition, scattering them to museums worldwide. In 2022 Germany transferred ownership of the Benin objects in its public museums to Nigeria; other museums still hold them. Looking at this plaque now means seeing a masterpiece, a historical document and an unsettled question of justice all at once.