The new architecture has 'opened' the walls so that the separateness of interior and exterior is suppressed. Walls no longer sustain since the system of construction is based upon the use of columns. This results in a new type of ground plan, an open ground plan, which is totally different from classical ones, since interior space and exterior space are interrelated.

quote from his unpublished writing, in 'Fundamental principles', 1930; as quoted in Theo van Doesburg, Joost Baljeu, Studio Vista, London 1974, p. 203