There are two of us, and as we light our way by the aid of a lantern through these vast halls we might be taken for a night watch on its round. We have just shut behind us and doubly locked the door by which we entered, and we know that we are alone, rigorously alone, although this place is so vast, with its endless, communicating halls, its high vestibules and great flights of stairs; mathematically alone, one might say, for this palace that we are in is one quite out of the ordinary, and all its outlets were closed and sealed at nightfall.