Had optical perception not evolved into something more than sensory perception, into super-sensory perception, then the present period would never have had the courage to discover the spiritual in matter. There would have been no fundamental difference between a painting by Picasso [from Picasso's so-called 'abstract' period] and one by Paulus Potter [Dutch painter in 17th century, famous for his painting of cows]

from 'Painting: from composition towards counter-composition'; in 'Painting and plastic art', 'De Stijl' – Theo van Doesburg, series XIII, 1 73-4, 1926, pp. 17-18