A large can is shown empty. The outside of the can is painted black and covered with lots and lots of white spots. Two silks are shown. One is a black silk which has been bleached white. The other is a white silk which has been dyed black. They are both placed in the can and the magic words incanted. Suddenly -- the black silk changes to white and the white silk changes to black. A miracle -- and you can show the can empty. Do it again. Place the two silks in the can. This time merely wave your hand over the can and the spots vanish. Now reach into the can and Wow -- the black silk is covered with white spots and the white silk is covered with black spots.