The Impressionists had tried to catch the momentary flicker of light; Paul Cézanne was not satisfied with that. "I want to make of Impressionism something solid and durable, like the art of the museums," he said. He sought not the fleeting but the unchanging structure beneath a landscape.

In the south of France, over the last twenty years of his life, he painted Mont Sainte-Victoire — the mountain rising above his native Aix-en-Provence — more than sixty times. The same mountain, but each time a different analysis. Cézanne summed up his way of seeing nature in a sentence: "Treat nature in terms of the cylinder, the sphere, and the cone." The brushstrokes no longer describe objects; each stroke is a plane of colour, a unit of volume. Mountain, sky, and the houses on the plain are woven with the same fabric; the aerial perspective between foreground and background is broken, the distant mountain as solid as the trees in front.

This is the moment painting stopped copying what it saw and began to reconstruct it. Colour does not imitate light; it builds space and volume itself — warm tones advance, cool tones recede. This method, which Cézanne called "small touches of colour that bind to one another," dissolves form and brings the reality of the surface forward.

The young Picasso and Braque found in these paintings the seed of Cubism; Matisse and nearly every modern painter called Cézanne "the father of us all." When he died in 1906 he was not a celebrated master; but the retrospective held a year after his death drew the map of twentieth-century art. The mountain itself still stands above Aix; the gaze that analysed it seeped into the painting of the century to come.