As a photographer Ansel Adams saw the natural world simultaneously as itself and as an art object. The realized perfection of many of his images derives from an abstract tendency working itself out in the dimensions of a large, vibrant terrain. This is a very different matter from the mild geometry of brick and shadow or the interminable search for "texture." In his best photographs, landscape and season, earth and light, are revealed in a grand mutuality - a moment so precisely visualized in tone and composition as to be mathematical, and yet so revelatory of earthly beauty as to be something else entirely.