The Spiritual Landscape identifies a charmed moment in the history of twentieth century avant-garde art -- a time when landscape, as a refuge for the soul and a source of spiritual nourishment, was equated with painting predicated on expressive colour and form. As the curators of the exhibition, Vivien Greene and Susan Cross, explain in the following essay, the theory of the spiritual aspect of art is directly connected to the origins of the Guggenheim Museum.