Discourse on painting.

Perspective, as it extends into painting, divides into three principal parts, of which the first concerns the diminution that the sizes of bodies undergo at various distances.

The second part is that which treats of the diminution of the colours of such bodies.

The third is that which diminishes the distinctness of the figures and outlines that those bodies have at various distances.

Perspective employs, across distances, two contrary pyramids: one of which has its angle in the eye and its base as far off as the horizon; the second has its base toward the eye and its angle at the horizon. But the first attends to the universal, embracing all the sizes of the bodies set before the eye - as would be a great landscape seen through a narrow chink, where a greater number of things is seen through such a chink the farther those things are from the eye; and thus the base is formed at the horizon and the angle in the eye, as I said above.

The second pyramid extends to a particular thing, which shows itself the smaller the farther it is removed from the eye; and this second perspective is born of the first.

The surface of every body partakes of the colour of the body that illuminates it, and of the colour of the air interposed between the eye and that body - that is, of the colour of the transparent medium interposed between the thing and the eye.

Among colours of the same quality, the second will never be of the same colour as the first, and this arises from the multiplication of the colour of the medium interposed between the thing and the eye.

Of every figure placed at a long distance, the distinctness of the smallest parts is lost first, and last of all are kept the largest parts, deprived of the distinctness of all their extremities, remaining oval or spherical in figure, with confused outlines.