Crowther emphasizes the extreme importance of the fact that an embodied subject is by definition an occupant of space. For Crowther, the basic symbolic structure of architecture starts from the enclosing and or declaring of space for functional purposes. This necessitates the connecting and or working of three-dimensional material. Pictorial art is three-dimensional in mainly virtual terms but, of course, architectural works are physically three-dimensional. Crowther explores many aspects of the uniqueness of pictorial art. Crowther argues that photography has its own unique symbolizing structure. Photographs work by causally capturing a single visible aspect of their subject. Autographic media such as drawing and painting create their subject matter through the artist's physical gestures. The relation between what a specific photograph shows, and the knowledge of the causal rigidity of photography as a physical and symbolic idiom, is the basic symbolic function which makes it one of the symbolic forms of visual art.