For the present at least [1909] I shall restrict my work to the ordinary world of the senses, since that is the world in which we still live. But nevertheless art even now form a transition to the finer regions, which perhaps I am incorrect in calling spiritual, for everything that has form is not yet spiritual, as I read somewhere. But it is nonetheless the path of ascension away from matter. Well dear Querido, with many heartfelt wishes, Piet Mondriaan.

In a letter to Israel Querido, Summer of 1909; published in the weekly magazine 'De Controleur' 23 Oct, 1909; as quoted in Mondrian, - The Art of Destruction, Carel Blotkamp, Reaktion Books LTD. London 2001, p. 36