The new architecture considers not only space, but also time to be an architectural value. The unity of space and time will give architecture a new form of appearance, which is more complete. This is what is meant by 'active space'.... the dissimilar space-cells develop eccentrically from the center to the borders of the cube, thereby granting a new plastic quality to the dimensions of height, width, depth, and time.

quote from his unpublished writing, in 'Fundamental principles', 1930; as quoted in Theo van Doesburg, Joost Baljeu, Studio Vista, London 1974, p. 203