Relief in Line-Drawing
What may be called the natural principle of relief—that system of light and shade by which a figure or any solid object is perceived as such by the eye—consists in each part of the form being thrown into more or less contrast by appearing as dark on light upon its background, more especially at its edges. A figure wholly dark, say in black drapery, appearing against a light ground, might be supposed to be flat if no cast shadow was seen; the same with the reverse—a light figure upon a dark ground—except that in this latter case, unless the light was very level and flat, a certain concentration of light upon the highest parts, or indicating a modulation of shadow in interstices, might betray its solidity (see p. [206]).
But if we place a figure so that the light falls from one side, we perceive that it at once stands out in bold relief in broad planes of light and shade, further emphasized by cast shadows (p. [207]).
It would be possible to represent or to express a figure or object so lighted by means of laying in the modulations and planes of shadow only, or by means of adding the light only on a toned ground. In sketching in black and white, it is a good plan to accustom oneself to complete as one goes along, as far as may be, putting in outline and shadow together; but this needs a power of direct drawing and a correctness of eye only to be gained by continual practice. A slight preliminary basis of light lines to indicate the position and proportions, and yet not strong enough to need rubbing out, is also a good method for those who do not feel certain enough for the absolutely direct method of drawing.
