Black cubes

From here I got here: http://www.theblackcubes.com/index.php

"999 black wooden cubes
The shape, appearence and dimensions of all the 999 cubes are exactly the same
Inside every cube there is something...
This thing has a precise sense while is closed in the cube
If you open the cube the meaning of this thing is irreparably lost
The only way to take possession of this meaning is to be inside the cube...
...But this is obviously impossible!"