The word deaccession is one of those bureaucratic coinages whose chief purpose is verbal obfuscation. If a museum director tells you he has “deaccessioned” eighteen Cézannes, you think for a second, “Oh, that’s nice” while you wonder exactly how to conjugate the verb “to deaccess.” What would happen if museum directors were more direct? Suppose, for example, that instead of saying “I have deaccessioned eighteen Cézannes” he spoke in plain English and said: “I have looted my collection of eighteen Cézannes in order to sell them and raise money to cover the budget shortfall I created by imprudent management.” It sounds rather different, doesn’t it?

As far as I have been able to discover, we have no reliable figures on the number of paintings and other types of cultural property that have been lost to the public as a result of...