Sign is symbol, symbol is sign. Consider:
*Powell goes to the United Nations so that the missile attacks on Baghdad and Basra can begin -- and, in the lobby of that grand building, Picasso's "Guernica" painting, which depicts the horrific results of the Nazi bombing of that Spanish town, is covered over prior to Powell's arrival. No use embarrassing the U.S. by reminding folks of what's in store for Iraqi civilians.
*Ashcroft, in his police-state zeal, begins shredding the Constitution's Bill of Rights with its guarantees of due-process of law, and, early on, has the huge lobby statue of the Goddess of Justice draped and covered over because of its exposed breast. How appropriate to shroud Justice so that she can't see what's being done in her name.
*First Lady Laura Bush cancels a poetry workshop at the White House because she suspects that a number of America's high-profile poets, in the sacred grounds of that seat of power, will raise the issue of the coming war with Iraq.
Did you notice the thread that unites these events? In all three cases, symbolic shrouds are placed over art, so that nobody will notice the bad things that are being done in American citizens' names.