红、黑、黄、蓝、灰构成

1921 is the year the familiar Mondrian arrives. He was 49, back in Paris after the First World War had kept him in the Netherlands for five years, and the sale of a painting to a Dutch acquaintance that year paid for a better studio on the rue du Depart, by the Montparnasse station, where he stayed until 1936. The year before, a Paris publisher had brought out his essay on neo-plasticism, which argued that painting should come down to straight lines, right angles, the three primary colours and the three non-colours, black, white and grey. The canvases of 1921 are the first that carry the programme through. This one stands upright, 80 by 50 centimetres, and it is in The Hague, in the museum that holds more of his work than any other.