Piet Mondrian realizes the importance of line. The line has almost become a work of art in itself; one can not play with it when the representation of objects perceived was all-important. The white canvas is almost solemn. Each superfluous line, each wrongly placed line, any color placed without veneration or care, can spoil everything – that is, the spiritual.
'Eenheid' no. 283, 6 November 1915; as quoted in Theo van Doesburg, Joost Baljeu, Studio Vista, London 1974, pp. 105-106