the harsh contrasts of tone:  everywhere hard lights are brought up against hard darks.  Harsh contrasts of tone produce much the same look of terror as harsh contrasts of line.  Battle pictures are usually, when good, full of these clashes of line and tone, and thrilling dramatic effects in which a touch of horror enters are usually founded on the same principle.  In the picture by Paolo Uccello in the National Gallery, reproduced on page 170 [Transcribers Note:  Plate XXXIX], a milder edition of this effect is seen.  The artist has been more interested in the pageantry of war and a desire to show off his newly-acquired knowledge of perspective, than anything very terrible.  The contrasts of line are here but confined to the smaller parts, and there are no contrasts of light and shade, chiaroscuro not being yet invented.  However, it will be seen by the accompanying diagram how consistently the harsh contrasts of line were carried out in the planning of this picture.  Notice the unconscious humour of the foreshortened spears and figure carefully arranged on the ground to vanish to the recently discovered vanishing point.

[Illustration:  Diagram XVII.

SHOWING THE CLASH OF LINES IN SYMPATHY WITH THE MARTIAL NATURE OF THIS
SUBJECT.]

[Illustration:  Plate XXXIX.

BATTLE OF ST. EGIDIO.  PAOLO UCCELLO (NATIONAL GALLERY)

Illustrating the effect of jarring lines in composition. (See diagram on opposite page.)

Photo Morelli]

* * * * *

Lines radiating in smooth curves from a common centre are another form employed to give unity in pictorial design.  The point from which they radiate need not necessarily be within the picture, and is often considerably outside it.  But the feeling that they would meet if produced gives them a unity that brings them into harmonious relationship.

There is also another point about radiating lines, and that is their power of setting up a relationship between lines otherwise unrelated.  Let us try and explain this.  In Panel A, page 174 [Transcribers Note:  Diagram XVIII], are drawn some lines at random, with the idea of their being as little related to each other as possible.  In B, by the introduction of radiating lines in sympathy with them, they have been brought into some sort of relationship.  The line 1-2 has been selected as the dominating line, and an assortment of radiating ones drawn about it.  Now, by drawing 7-8, we have set up a relationship between lines 3-4, 5-6, and 1-2, for this line radiates with all of them.  Line 9-10 accentuates this relationship with 1-2.  The others echo the same thing.  It is this echoing of lines through a composition that unites the different parts and gives unity to the whole.