2. When a picture is an accessory, decorating an object whose use would forbid too elaborate finish, and which would also be too costly. Such are the paintings which ornament screens, work-boxes, tables, &c.; in this case the objects preferable as models, are those whose beauty of colours and simplicity of form are so remarkable as to attract the eye by simplicity of outline, and by vivid colours: such are birds, insects, flowers, &c. SECTION III. ON COLOURING IN PAINTING. CHAPTER I. _On Colouring._ 301. _True or absolute colouring_ is the faithful reproduction in painting of the modifications that light enables us to perceive in the objects taken for models. 302. In the ordinary use of the word _colouring_, we allude to the more or less perfect manner in which the painter has complied with the rules, 1. _Of aërial perspective._ 2. _Of the harmony of local colours, and of the colours of the different objects composing the picture._ ARTICLE I. _Of Aërial Perspective._ 303. We must not believe that the employment of many colours in a composition is indispensable to give the epithet of _colourist_ to the artist, for in pictures painted in one colour only, the simplest of all, in which we only distinguish two colours including white, the artist may be honoured with the title of _colourist_, if his work presents lights and shades distributed as they are upon the model. To convince ourselves of the justice of the expression, it will suffice to remark that the model might very well appear to the painter coloured with a single colour, modified by light and shade. In the same sense this epithet may be applied to the engraver, who, by means of his burin, reproduces a picture as faithfully as possible, in respect both to the aërial perspective of its different planes, and to the relief of each particular object. 304. A painter who has faithfully reproduced the aërial perspective, with all its modifications of white and coloured light and of shades, has effected a _true or absolute colouring_, which, however, may not be universally deemed as perfect as that in which this quality of absolute colouring is not found, at least in the same degree of perfection. _Imperfectly faithful imitation._ 305. _A painter may have perfectly seized upon all the modifications of white and coloured light, but in his imitation, some of these modifications are more strongly marked than in nature._