The eye which turns from a white object in the light of the sun and goes into a less fully lighted place will see everything as dark.

The light for drawing from nature should come from the North in order that it may not vary. And if you have it from the South, keep the window screened with cloth, so that with the sun shining the whole day the light may not vary. The height of the light so arranged as that every object shall cast a shadow on the ground of the same length as itself.

Shadows which you see with difficulty, and whose boundaries you cannot define... these you should not represent as finished or sharply defined, for the result would be that your work would seem wooden.

To any white body receiving the light from the sun, or the air, the shadows will be of a bluish cast.

The light and heat of the universe comes from the sun, and its cold and darkness from the withdrawal of the sun.

The first of all single colors is white ... We shall set down white for the representative of light, without which no color can be seen; yellow for the earth; green for water; blue for air; red for fire; and black for total darkness.

Shadow is the obstruction of light. Shadows appear to me to be of supreme importance in perspective, because, without them opaque and solid bodies will be ill defined; that which is contained within their outlines and their boundaries themselves will be ill-understood unless they are shown against a background of a different tone from themselves.

Darkness is absence of light. Shadow is diminution of light.

It is a far worthier thing to read by the light of experience than to adorn oneself with the labors of others.