319. We can establish three conditions in the appearance of the same object relatively to the state of the eye; in the first, the organ simply perceives the image of the object without taking into account the distribution of colours, light, and shade; in the second, the spectator, seeking to understand this distribution, observes it attentively, when the object presents to him all the phenomena of simultaneous contrast of tone and colour that it is capable of exciting in him. In the third case, the organ, from the prolonged impression of the colours, possesses in the highest degree a tendency to see the complementary of these colours; these different states of the organ being continuous. I have no doubt that the dull colouring with which many artists of merit have been reproached is partly due to this cause, as I shall show more minutely hereafter. _Utility of this Law to facilitate the prompt Imitation of Modifications of Light on the Model._ 320. The painter, knowing that the impression of one colour beside another is the result of the mixture of the first with the complementary of the second, has only to estimate mentally the intensity of the influence of this complementary, to reproduce faithfully in his imitation the complex effect which he has before his eyes. 321. A painter wishing to imitate a white stuff with two contiguous borders, one red, the other blue, perceives each of them changed by the influence of their reciprocal contrast; thus the red becomes more and more orange, in proportion as it approaches the blue, as this latter becomes more and more green as it approaches the red. The painter, therefore, making the borders of a single red and a single blue, reduced in some parts by white or by shade, will reproduce the effects he wishes to imitate. Whenever it is found that the painting is not sufficiently marked, he is sure of what he must add without departing from the truth, farther than by exaggerating a little (305). 2. A grey pattern drawn upon a yellow ground: the ground may be of paper, silk, cotton or wool; according to its contrast, the design will appear of a lilac or a violet colour (66). The painter who would imitate this object, can reproduce it faithfully with grey. But if a painter, ignorant of the reciprocal influence of blue and red, convinced that he must represent what he sees, adds green to his blue, and orange to his red; as in the second example, he will trace a pattern more or less violet upon the yellow ground. Now, supposing that the painter had perfectly seized the modifications of the model, and, subsequently, had retouched his copy sufficiently to produce a perfectly faithful effect, it is evident it would have been perfect only after a number of trials, since he must have effaced what was first done. 3. I cite a third example of the influence of contrast, not relating to colours, like the two preceding, but to the different tones of the same colour, contiguous to each other.