Most of the earliest forms of drawing known to us in history, like those
of the child we were discussing in the last chapter, are largely in the
nature of outline drawings. This is a remarkable fact considering the
somewhat remote relation lines have to the complete phenomena of vision.
Outlines can only be said to exist in appearances as the boundaries of
masses. But even here a line seems a poor thing from the visual point of
view; as the boundaries are not always clearly defined, but are
continually merging into the surrounding mass and losing themselves to
be caught up again later on and defined once more. Its relationship with
visual appearances is not sufficient to justify the instinct for line
drawing. It comes, I think, as has already been said, from the sense of
touch. When an object is felt there is no merging in the surrounding
mass, but a firm definition of its boundary, which the mind
instinctively conceives as a line.

There is a more direct appeal to the imagination in line drawing than in
possibly anything else in pictorial art. The emotional stimulus given by
fine design is due largely to line work. The power a line possesses of
instinctively directing the eye along its course is of the utmost value
also, enabling the artist to concentrate the attention of the beholder
where he wishes. Then there is a harmonic sense in lines and their
relationships, a music of line that is found at the basis of all good
art. But this subject will be treated later on when talking of line
rhythm.

Most artists whose work makes a large appeal to the imagination are
strong on the value of line. Blake, whose visual knowledge was such a
negligible quantity, but whose mental perceptions were so magnificent,
was always insisting on its value. And his designs are splendid examples
of its powerful appeal to the imagination.