Rules on opaque surfaces, color and edges
Lettered precepts on how surface, medium and distance govern a body's color and relief
The leaf finishes the treatment of smoke, advising that smokes appear with their flames at the illuminated hearts of their densest billows and that the highest mountains stand out more than their bases, as with mist. A note by the compiler records that below this chapter there stood a pen-and-watercolor drawing of a mountain breaking open with flames playing in its ruptures, marvelous and lifelike to see. Two lettered chapters follow: [471] gives rules a, b, c that an opaque surface partakes of the color of its object and of the transparent medium, and that a body's edges grow less distinct with distance; [472], cited from Book B folio 17, adds rules f, d, e on where a body is most shadowed or lit, how object distance and power alter its color, and how things between light and shadow show greatest relief.
On this page
Smoke and flame among the mountains
Let smokes be seen in various places with their flames at the illuminating beginnings of their densest billows. And let the highest mountains be more evident than their roots, as is seen to happen with mists.
Note of a lost pen-and-wash drawing of a burning mountain
The compiler records that below this chapter there was a breaking-open of a mountain, within whose ruptures flames of fire played. It was drawn with the pen and shaded with watercolor, a marvelous and lifelike thing to see.
Surface partakes of object and medium (rules a, b, c)
a. The surface of every opaque body partakes of the color of its object, the more so as that surface approaches greater whiteness. b. It also partakes of the color of the transparent medium between the eye and the surface, the denser that medium or the greater the space. c. The edges of opaque bodies are less known the more distant they are from the eye.
Shadow, object-power and relief (rules f, d, e)
f. That part of an opaque body is most shadowed or lit that is nearest the shadowing body or the luminous one. d. A surface partakes of its object's color with greater or lesser impression as the object is nearer, more remote, or of greater or lesser power. e. Things seen between the light and the shadow show greater relief than those wholly in light or in shadow.