Drawing

To understand the degrees of dimming of light caused by the distance between objects and their distance from the viewer, one must examine the shadows and the various degrees of strength they gain or lose by their distance. It's important to consider how light reflects, the dimming it causes on reflected shadows, and how reflected bodies darken or lighten depending on their distance from the viewer's eye.

Regarding color, one must examine the change colors undergo with distance from our eyes. The same red placed at twelve feet or twelve yards is not the same, and this applies to all colors due to the distance the light rays travel to reach our eyes and the air between objects. Finally, it's noted that the color of objects no longer appears the same in shadow as in light; it becomes muted, dull, and blended with the color of nearby objects that send reflected light.

(a) Note that objects close to the eye reflect more than those further away, and their colors appear more vivid, not only in light but even in shadows, because they reflect more and lose less of their color than distant objects. Their color almost completely fades in the shadows and weakens in light. When the air is not filled with vapors, these shadows are quite dark without a discernible color. However, when the air is filled, the shadows are less black and take on the color caused by the vapors illuminated by sunlight. This color of vapors, or in other words of the air, varies with the time of day. In the morning at sunrise, shadows appear bluish and often even violet; at sunset, shadows have a hint of blue, not because these shadows are actually of this color, as all shadows are inherently gray, meaning:

Translation Notes

Distinctions like "twelve toises" refer to an old French unit of measurement roughly equivalent to two meters per toise.