In a Dutch landscape we cannot expect the rich colouring of Italy. The colouring of Holland is low toned, and tender gradations lead away to the low and level horizon. The canals are sluggish and grey, and the clouds often heavy and dark. We saw how the brilliant skies and pearly buildings of Venice made Venetian painters the gayest colourists of the world. So the Dutch painters took their sober scale of landscape colouring as it was dictated to them by the infinitely varied yet sombre loveliness of their own land. In the great flat expanses of field, intersected by canals and dotted with windmills, the red brick roof of a water-mill may look 'loud,' like an aggressive hat. But the shadows cast by the clouds change every moment, and in flat country where there is less to arrest the eye the changes of tone are more marked. In an etching, Rembrandt could leave a piece of white paper for the spot of highest sunlight, and carry out all the gradations of tone in black and white, until he reached the spot of darkest shadow. A painted landscape he indicated in the same way by varying shades of dull brown. In all of them you seem to feel the interposition of the air between you and the distant horizon at which you are looking. What else is there? At each point in the picture the air modifies the distinctness with which you can see the objects. This consciousness of air in a picture of low horizon is a very difficult thing to describe and explain. We know when it is there and when it is not. It has to be seen, to be enjoyed, and recorded. Holbein painted Edward VI. standing, so to speak, in a vacuum. Every line of his face is sharply defined. In real life air softens all lines, so that even the edge of a nose in profile is not actually seen as a sharp outline. The figures in Richard II.'s picture stand in the most exhausted vacuum, but Hubert van Eyck had already begun to render the vision or illusion of air in his 'Three Maries.' In this respect he had learnt more than the early painters of the Italian Renaissance; but Raphael and the Venetians, especially Giorgione and Titian, sometimes bathed their figures in a luminous golden atmosphere with the sun shining through it.