We came into the shadow of the building and stumbled to the side of it away from the direction from which the shots had come. Grasshoppers buzzed out of the weeds in fierce brown flurries, some of them lighting on our clothes. There was the sound of dry thunder down the valley. This barracks had a door—a wooden door on a rail, large enough to admit dozens of people at once. But it was closed, and there was a brass latch and a padlock on it.

So we had no real shelter—just some shade and a moment’s peace.

I used the time to put a fresh handkerchief on Percy’s wound and to bind it with a strip of cloth torn from my own shirt.

“Thank you,” Percy said breathlessly.

“Welcome. The problem now is how to get back to the carriage.” We had no weapons, and we could hardly withstand a siege, no matter where we hid. Our only hope was escape, and I could not see any likely way of achieving it.

Then the question became moot, for the man who had tried to kill us came around the corner of the barracks.

“Why do you want to make these pictures?” Elsie asked yet again, from a dim cavern at the back of my mind.

In an adjoining chamber of my skull a different voice reminded me that I wanted a drink, a strong one, immediately.

The ancient Greeks (I imagined myself telling Elsebeth) believed that vision is a force that flies out from the eyes when directed by the human will. They were wrong. There is no force or will in vision. There is only light. Light direct or light reflected. Light, which behaves in predictable ways. Put a prism in front of it, and it breaks into colors. Open a shuttered lens, and some fraction of it can be trapped in nitrocellulose or collodion as neatly as a bug in a killing jar.