The text discusses basic concepts of aerial perspective, focusing on shadows and how light affects them. It explains how objects appear smaller and less distinct as they move away due to the transparent air filling the space between planes. The passage emphasizes the importance of accurately depicting shadows and details to maintain the natural depth and realism of a painting.
A Few Basic and Very Simple Notions of Aerial Perspective.
On Shadows.
A round object or one composed of several faces usually has one side illuminated and one side deprived of light: this absence of light is called shadow. The transition from shadow to light is known as half-tone or half-tint. There are half-tones of varying strength.
We have seen that objects appear to diminish as they move away from the observer; however, it is not only their lines that diminish, but the shadows and lights of these bodies appear to decrease at the same rate. Thus, the shadows of objects in the foreground are the darkest and most vivid; those in the background are less dark and less vigorous, and this continues in a precise decreasing progression. It was shown (plate 2, fig. 1) that objects placed at double the distance appear half their size to the eye, with their shadows diminishing in the same proportion. An object placed at ten feet, then twenty feet away, will not only appear twice as small but also twice as less dark or shaded, and the same applies to lights and half-tones or half-tints.
The cause of this diminution is easy to understand: the space between the foreground and background is filled with a mass of air. Although this air is transparent, it always intercepts some light and produces much the same effect as a very light gauze through which one sees the background. This gauze is sometimes actually used in theater decorations to produce the illusion of a more or less distant background. From the second to the third plan, there's again a mass of air or a curtain of gauze, and so on; from this comes the weakening of shadows, colors, lights, and at the same time, the details of objects cease to be seen distinctly, leaving only the masses visible. Therefore, if one clumsily makes a too-strong touch or draws a detail too distinctly on a distant plane, that plane, instead of seeming to recede, would appear to come forward and destroy the effect of a painting that should represent nature faithfully.
Translation Notes:
1. Demi-ton/Demi-teinte: Translated as half-tone or half-tint, these terms refer to the gradual range of tones between light and shadow.
2. Plan: Refers to different planes or levels of perspective in art, a concept important in creating depth in drawings.