"I insist on astonishment," said Graciela Iturbide (b. 1942). To make photographs more astonishing than those of Graciela Iturbide would be a challenge, indeed. Not more shocking. That is a different impulse and this Mexican photographer does not stoop to conquer; instead, she visually embraces her unusual subjects, especially those operating outside the norm. Of course, the norm in Mexico is always in question and there are abundant opportunities there to take pictures of the outrageous and bizarre. Such works are common to the point of cliché. Iturbide is the exception as she composes her pictures with compassion.