The complete programme, however, did not consist of painting in bright hues, but, generally speaking, in seizing truth of colour and altogether renouncing artificial harmony in a generally accepted tone. Thus, after the painting of daylight and sunlight was learnt, a further claim had still to be asserted: the ideal of truth in painting had to be made the keynote in every other task. For in the sun, light is no doubt white, but in the recesses of the forest, in the moonshine, or in a dim place, it shines and is at the same time charged with colour. Night, or mist, with its hovering and pervasive secrets, is quite as rich in beauties as the radiant world of glistening sunshine. After seeing the summer sun on wood and water, it was a relief for the eye to behold the subdued, soft, and quiet light of a room. Upon the older and rougher painting of free light there followed a preference for dusk, which has a softness more picturesque, a more tender harmony of colours, and more geniality than the broad light of day. Artists studied clare-obscure, and sought for an enhancement of colour in it; they looked into the veil of night, and addressed themselves to a painting of darkness such as could only have proceeded from the _plein-air_ school. For this darkness of theirs is likewise full of atmosphere, a darkness in which there is life and breath and palpitation. In earlier days, when a night was painted, everything was thick and opaque, covered with black verging into yellow; to this latter error artists were seduced by the crusts of varnish upon old pictures. Now they learnt to interpret the mysterious life of the night, and to render the bluish-grey atmosphere of twilight. Or if figures were to be painted in a room, artists rendered the circulation of the air amid groups of people, which Correggio called "the ambient" and Velasquez "respiration." And there came also the study of artificial illumination--of the delicate coloured charm of many-coloured lanterns, of the flaring gas or lamp-light which streams through the glass windows of shops, flaring and radiating through the night and reflected in a blazing glow upon the faces of men and women. Under these purely pictorial points of view the gradual widening of the range of subject was completed.