[Footnote: 13. From the character of the handwriting I infer that
this passage was written before the year 1490.].

15.

ON PAINTING AND PERSPECTIVE.

The divisions of Perspective are 3, as used in drawing; of these,
the first includes the diminution in size of opaque objects; the
second treats of the diminution and loss of outline in such opaque
objects; the third, of the diminution and loss of colour at long
distances.

[Footnote: The division is here the same as in the previous chapter
No. 14, and this is worthy of note when we connect it with the fact
that a space of about 20 years must have intervened between the
writing of the two passages.]

16.

THE DISCOURSE ON PAINTING.

Perspective, as bearing on drawing, is divided into three principal
sections; of which the first treats of the diminution in the size of
bodies at different distances. The second part is that which treats
of the diminution in colour in these objects. The third [deals with]
the diminished distinctness of the forms and outlines displayed by
the objects at various distances.