erful appeal to the imagination.

On this basis of line drawing the development of art proceeded. The
early Egyptian wall paintings were outlines tinted, and the earliest
wall sculpture was an incised outline. After these incised lines some
man of genius thought of cutting away the surface of the wall between
the outlines and modelling it in low relief. The appearance of this may
have suggested to the man painting his outline on the wall the idea of
shading between his outlines.

At any rate the next development was the introduction of a little
shading to relieve the flatness of the line-work and suggest modelling.
And this was as far as things had gone in the direction of the
representation of form, until well on in the Italian Renaissance.
Botticelli used nothing else than an outline lightly shaded to indicate
form. Light and shade were not seriously perceived until Leonardo da
Vinci. And a wonderful discovery it was thought to be, and was, indeed,
although it seems difficult to understand where men's eyes had been for
so long with the phenomena of light and shade before them all the time.
But this is only another proof of what cannot be too often insisted on,
namely that the eye only sees what it is on the look-out for, and it may
even be there are things just as wonderful yet to be discovered in
vision.

But it was still the touch association of an object that was the
dominant one; it was within the outline demanded by this sense that the
light and shade were to be introduced as something as it were put on the
object. It was the "solids in space" idea that art was still appealing
to.

"The first object of a painter is to make a simple flat surface appear
like a relievo, and some of its parts detached from the ground; he who
excels all others in that part of the art deserves the greatest
praise,"[1] wrote Leonardo da Vinci, and the insistence on this
"standing out" quality, with its appeal to the touch sense as something
great in art, sounds very strange in these days. But it must be
remembered that the means of creating this illusion were new to all and
greatly wondered at.

[Footnote 1: Leonardo da Vinci, _Treatise on Painting_, paragraph 178.]

And again, in paragraph 176 of his treatise, Leonardo writes: "The
knowledge of the outline is of most consequence, and yet may be acquired
to great certainty by dint of study; as the outlines of the human
figure, particularly those which do not bend, are invariably