The problem which Mondrian undertook to solve in nr. 116 [a new painting of Mondrian, exhibited in a group-exhibition in the Stedelijk Museum in 1915 in Amsterdam] was handled very successfully. This work spiritually dominates all others. It gives the impression of Repose; the repose of the soul. Its pre-determined structure embodies 'becoming' rather than 'being'. This represents a true element in art, for art is not 'being', but 'becoming'. The idea of 'becoming' has been expressed in black and white.... Through years of hard work my own experiences have led me, before I came to know the theories of Uexkuell or Picasso, to prefer the use of the white-black-grey palette in works of a purely spiritual content...

In the Dutch art-magazine: 'Eenheid' (in Dutch: Unity) no. 283, 6 November 1915; as quoted in Theo van Doesburg, Joost Baljeu, Studio Vista, London 1974, p. 105