Precepts on Illumination, Distance and Colour (from Libro A)
Short rules on lighting, loss of image with distance, and transparent media
Five short precepts of the Treatise on Painting, each cited to Leonardo's now-lost 'Libro A' (sheets 16 and 18) and labelled a-d. They state that the part of an object nearest the light is most illuminated; that the image and substance of things weaken with every degree of distance; that colours must be diminished together with the bodies they clothe; that a greater transparent interposition transmutes an object's colour toward that of the interposed body; and that an object lying on the central line between light and eye is wholly deprived of light. The notes bind together illumination, aerial perspective and the optics of transparent media.
On this page
The most illuminated part faces the light
That part of the object will be most illuminated which is nearest to the luminous body that lights it. Marked a and cited to Libro A, sheet 18.
Image and colour weaken with distance
The likeness and substance of things lose degrees of power at every degree of distance: the more remote the thing from the eye, the less its image penetrates through the air. Colours are to be diminished together with the bodies to which they are applied. Marked b and cited to Libro A, sheets 18 and 16.
Transparent interpositions transmute colour
The greater the transparent interposition between the eye and the object, the more the colour of the object is changed into the colour of the interposed transparent body. Marked c and cited to Libro A, sheet 16.
An object on the light's central line is deprived of light
When the object comes between the eye and the light, along the central line running between the centre of the light and the eye, that object is then totally deprived of light. Marked d and cited to Libro A, sheet 16.