WHERE A SPECTATOR SHOULD STAND TO LOOK AT A PICTURE.

Supposing _a b_ to be the picture and _d_ to be the light, I say
that if you place yourself between _c_ and _e_ you will not
understand the picture well and particularly if it is done in oils,
or still more if it is varnished, because it will be lustrous and
somewhat of the nature of a mirror. And for this reason the nearer
you go towards the point _c_, the less you will see, because the
rays of light falling from the window on the picture are reflected
to that point. But if you place yourself between _e_ and _d_ you
will get a good view of it, and the more so as you approach the
point _d_, because that spot is least exposed to these reflected
rays of light.

III.

THE PRACTICAL METHODS OF LIGHT AND SHADE AND AERIAL PERSPECTIVE.

Gradations of light and shade.