The mirror promises so much and gives so little, it is a pool of swarming ideas or neoplatonic archetypes and repulsive to the realist. It is a vain trap, an abyss, nevertheless the cold distant people of the Ultramoderne installed themselves in many versions of the Hall of Mirrors. They lived in interiors of gloss and glass, in luminous skyscrapers, in rooms of rarefied atmospheres and airless delights. The overuse of the mirror turned buildings, no matter how solid and immobile, into emblems of nothingness. building exteriors were massive and windows were often surrounded by tomb-like mouldings and casements, but the interior mirrors multiplied and divided 'reality' into perplexing, impenetrable, uninhabitable regions. The walls outdoors were ultra physical, while the walls indoors were ingraspable and vain. The purist is vain enough to imagine he is pure, but this ultimate viewpoint frightens the naturalist. The 'window' and the 'mirror' are secret sharers of the same elements. The window contains nothing, while the mirror contains everything. Consider them both, and you will find it impossible to escape their double identity.

Robert Smithson, 'Ultramoderne' in The Writings of Robert Smithson (New York University Press, 1979) p. 50