Every point is the termination of an infinite number of lines, which diverge to form a base, and immediately, from the base the same lines converge to a pyramid [imaging] both the colour and form. No sooner is a form created or compounded than suddenly infinite lines and angles are produced from it; and these lines, distributing themselves and intersecting each other in the air, give rise to an infinite number of angles opposite to each other. Given a base, each opposite angle, will form a triangle having a form and proportion equal to the larger angle; and if the base goes twice into each of the 2 lines of the pyramid the smaller triangle will do the same.

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

. . .

The elements of perspective--Of the Point.

42,

43,

44,

45,

Of the line.

47,

48,

The nature of the outline.

Definition of Perspective.

Experimental proof of the existence of the pyramid of sight.

52,

53,

The relations of the distance points to the vanishing point.

55,

How to measure the pyramid of vision.

The Production of pyramid of Vision.

58,

59,

60,

61,

62,

63,

Proof by experiment.

65,

General conclusions.

That the contrary is impossible.

A parallel case.

The function of the eye as explained by the camera obscura.

70,

The practice of perspective.

72,

Refraction of the rays falling upon the eye.

74,

The inversion of the images.

The intersection of the rays.

77,

78,

79,

80,

81,

. . .