Warner acquired the pieces legally. However, at the time of the expedition, China was in a state of political and economic chaos, caused mostly by the influence of European powers. In the midst of this situation, the Chinese hardly had time to fully value a few relics in remote northern areas.

Like Fletcher, Warner had little trouble removing some of the wall paintings and sculptures. Moreover, he could claim that he was doing a good deed by preserving the pieces from possible destruction.

Unlike the case of either the Omaha collection or the Elgin marbles, no one has demanded the return of the Tun-huang pieces. A large number of similar wall paintings remain in the caves, and the pieces are not held to be the "crown jewels" of China.

But the fact that nobody has asked for them does not free Harvard from the moral obligation to consider returning the artifacts. At the very least, the museum should examine the historical conditions surrounding the acquisitions. And although not "crown jewels," the Tun-huang wall paintings and sculptures are highly prized because they reflect a unique mixture of styles influenced by silk Road trade.

Harvard has a special obligation in this case because--unlike the bulk of the museum's collection, comprised of gifts from private donors--these pieces were collected by a Harvard professor. The University is more directly responsible for the conditions under which the artifacts were obtained.

Many similar cases exist at Harvard museums and at museums around the world. Certainly the categorical return of every work of art to its country of origin is absurd. But some art objects, such as the sacred material of the Omaha, the Elgin marbles and the cave paintings of Tun-huang, are integral to their original culture.

There are no clear and easy answers in this debate. But a thorough investigation of the conditions surrounding the acquisition of museum collections is required as we emerge from the imperialist age into a new era of multicultural harmony and co-existence.