29

Differences of perception by one eye and by both eyes.

Let the object in relief t be seen by both eyes; if you will look at the object with the right eye m, keeping the left eye n shut, the object will appear, or fill up the space, at a; and if you shut the right eye and open the left, the object (will occupy the) space b; and if you open both eyes, the object will no longer appear at a or b, but at e, r, f. Why will not a picture seen by both eyes produce the effect of relief, as [real] relief does when seen by both eyes; and why should a picture seen with one eye give the same effect of relief as real relief would under the same conditions of light and shade?

[Footnote: In the sketch, m is the left eye and n the right, while the text reverses this lettering. We must therefore suppose that the face in which the eyes m and n are placed is opposite to the spectator.]

Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.

28 * 30

Notebooks of Leonoardo da Vinci

I: Prolegomena and General Introduction to the Book on Painting.

. . .

General introductions to the book on Painting.

10,

11,

12,

The plan of the book on Painting.

14,

15,

16,

The use of the book on Painting.

Necessity of theoretical knowledge.

19,

The function of the eye.

21,

22,

23,

Variability of the eye.

Differences of perception by one eye and by both eyes.

26,

27,

28,

The comparative size of the image depends on the amount of light.

30,

31,

32,

33,

34,

35,

36,

37,

38,

. . .