a curious gallery visitor walks around a tall, thin metal sculpture to view it from different angles. She stops directly in front of the sculpture's narrowest side, seeing only a thin vertical line. The sculpture appears almost invisible from this sideways position, showing just its edge. From her previous position, the sculpture looked wide and detailed, but now it's just a slim outline. Other visitors nearby view the same sculpture from different angles, seeing its full width and artistic details. the sculpture being viewed edge on, with only its narrow edge visible to the observer