"Empty space," said the driver. "There's a funny thing to think about. The back of the van is full of empty space. I brought it from my town. But I've opened the doors several times since I left. So is it still empty space from my town or is it now several different new empty spaces? This is the sort of thing one thinks about sometimes. If the back of the van were full of chairs the question wouldn't arise. One assumes that the space between the chairs remains the same all through the trip. Empty space, however, is something else."
from The Lion of Boaz-Jachin and Jachin-Boaz