It was the practice of the earlier artists to paint on light grounds. This ground consisted of gypsum, and was thickly spread on linen or panel, and then levigated. After the outline was drawn, the subject was washed in with a blackish or brownish colour. Pictures prepared in this manner for colouring are still in existence, by Leonardo da Vinci, and Fra Bartolomeo; there are also several by Guido.--Note I I. 903. When the artist proceeded to colour, and had to represent white draperies, he sometimes suffered the ground to remain untouched. Titian did this latterly when he had attained the greatest certainty in practice, and could accomplish much with little labour. The whitish ground was left as a middle tint, the shadows painted in, and the high lights touched on.--Note K K. 904. In the process of colouring, the preparation merely washed as it were underneath, was always effective. A drapery, for example, was painted with a transparent colour, the white ground shone through it and gave the colour life, so the parts previously prepared for shadows exhibited the colour subdued, without being mixed or sullied. 905. This method had many advantages; for the painter had a light ground for the light portions of his work and a dark ground for the shadowed portions. The whole picture was prepared; the artist could work with thin colours in the shadows, and had always an internal light to give value to his tints. In our own time painting in water colours depends on the same principles. 906. Indeed a light ground is now generally employed in oil-painting, because middle tints are thus found to be more transparent, and are in some degree enlivened by a bright ground; the shadows, again, do not so easily become black. 907. It was the practice for a time to paint on dark grounds. Tintoret probably introduced them. Titian's best pictures are not painted on a dark ground. 908. The ground in question was red-brown, and when the subject was drawn upon it, the strongest shadows were laid in; the colours of the lights impasted very thickly in the bright parts, and scumbled towards the shadows, so that the dark ground appeared through the thin colour as a middle tint. Effect was attained in finishing by frequently going over the bright parts and touching on the high lights. 909. If this method especially recommended itself in practice on account of the rapidity it allowed of, yet it had pernicious consequences. The strong ground increased and became darker, and the light colours losing their brightness by degrees, gave the shadowed portions more and more preponderance. The middle tints became darker and darker, and the shadows at last quite obscure. The strongly impasted lights alone remained bright, and we now see only light spots on the painting. The pictures of the Bolognese school, and of Caravaggio, afford sufficient examples of these results. 910.