The serious student will progress most rapidly if in his practice he pursues both these extremes of vision to the utmost. He will then achieve confidence and certainty in seeing and reproducing and find most quickly his own personal means of expression. It is always wrong for a beginner to start with a one-sided program, with a preconceived notion of how to see and how to reproduce. It is equally wrong for the teacher to force his own individuality onto his students.
We have shown how in first attempting to make the ambiguous outline into an unambiguous representation, it is often the tone value that gives a thing substance. Tone value can also indicate the kind of material the subject is made of. The beholder always likes to know if he is looking at stone, wood, or cloth, whether the material is rough or smooth, soft or hard, dense or loosely assembled, etc. Lines, or strokes, can indicate material.
Although it is not always ideal, the relatively stubborn "stroke" can give a peculiarly attractive rendering of material. However, color may sometimes seem a more suitable means of communicating fluid and other uniform surfaces.
The simplest representation of a surface is made with parallel strokes, or hatching. But because a surface is seldom depicted parallel to the plane of the picture, parallel hatching will often throw the picture out of alignment. The lines of the hatching, like any strokes, tend to indicate a direction which is unconsciously associated with the vanishing point of spatial perspective.
Either the hatching must take this into account or a different method of indicating surface must replace it: one conveying texture. Texture is essentially a means of representing a surface without implying any direction. The methods are innumerable. Even crosshatching loses any definite sense of direction, since it consists of four different directions, one pair perpendicular to the other.
It is possible to represent almost every material with textures of dots and lines. This can be practiced at every turn. Once you can fill in textures, you progress to drawing the textured areas without any outline. At first you need a guide: a thin pencil outline which is erased after the texture has been filled in with pen and ink. In time you will be able to achieve directly, without a guiding outline, the striking effect of textured areas which touch without outlines. These are the means of expression of impressionistic vision, of things seen as surfaces.
A uniform texture of equal tone value can be easily developed into one with gradations of tone which fades away. It can then be used for the representation both of receding perspective and of modeling in the round.
When talking of the sketch, we were constantly referring to broken and incomplete strokes. They do not generally end abruptly, but are faded out, either becoming narrower or lighter in tone, or both, according to the material used for drawing. If you use a pen which does not respond to alterations of pressure, the line disappears in dashes or dots.
In the same way that gradations in the weight of the texture produce an effect of volume or of distance, so a heavier or lighter line can give the illusion of space or volume, even if the line is used only as a contour. It can raise the outlined object out of the picture plane clearly enough to make shading or complete rendering of the material by texture unnecessary. Thickening of the line conveys shadow or nearness to the beholder; a faint line betokens light or distance. In the strongest light, the line can disappear altogether.