All the problems of perspective are made clear by the five terms of mathematicians, which are:—the point, the line, the angle, the superficies and the solid. The point is unique of its kind. And the point has neither height, breadth, length, nor depth, whence it is to be regarded as indivisible and as having no dimensions in space. The line is of three kinds, straight, curved and sinuous and it has neither breadth, height, nor depth. Hence it is indivisible, excepting in its length, and its ends are two points. The angle is the junction of two lines in a point.

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

General remarks on perspective.

40,

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,

. . .