最近、ちょっとダビンチのメモを読んでいるのだが、16世紀の初頭にして、現在、知覚心理学でいわれている奥行き知覚の手がかりの多くを指摘している。

 14. On the Three Branches of Perspective.

There are three branches of perspective; the first deals with the reasons of the (apparent) diminution of objects as they recede from the ey, and is known as Diminishing Perspective. - The second contains the way in which colours vary as they recede from the eye.  The third and last is concerned with the explanation of how the objects (in a picture) ought to be less finished in proportion as they are remote (and the names are as follows):

Linear Perspective.  The perspective of color.  The perspective of disappearance.

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.

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.

17. On the Sections of (the Book on) Painting

The first thing in painting is that the objects it represents should appear in relief, and that the grounds surrounding them at different distances shall appear within the vertical plane of the foreground of the picture by means of 3 branches of perspective, which are: the diminution in the distinctness of the forms of the objects, the diminution in their magnitude; and the diminution in their colour.  And of these 3 classes of perspective the first results from (the structure of) the eye, while the other two are caused by the atmosphere which intervenes between the eye and the objects seen by it.  The second essential in painting is appropriate action and a due variety in the figures, so that the men may not all look like brothers.

Leonardo Da Vinci "The Notebooks of Leonardo Da Vinci" (1513-1516)