Perspective, the Bridle and Rudder of Painting
Waves blur the bottom, foam pales with depth, and figure size betrays distance
A leaf of the Trattato della pittura, header TERZA, folio numbered 160, closing the account of water's transparency and stating a celebrated precept. Swift water, ruffled by waves, twists the images of the bed like flexuous mirrors and shows its figures confusedly; a marginal note refers the demonstration to the 42nd proposition of the perspective. A short chapter on foam holds that it grows less white the deeper it lies, as the color turns green under more water. The page ends with the precept that perspective is the bridle and rudder of painting: the size of a painted figure declares its distance. Two small pen diagrams accompany the text.
On this page
Waves distort the images of the water-bed
Swift water cannot show its bed, because the waves' obliquities, curvatures, summits and intervals carry the images out of our straight line of sight and twist them to various aspects, showing the figures confusedly. This is likened to flexuous mirrors, mixed of straight, convex, and concave surfaces.
The foam of water (chapter 508)
Foam shows less white the further it lies from the surface, for the natural color of a submerged thing turns more toward the water's green the greater the amount of water above it.
Precept: perspective is the bridle and rudder of painting (chapter 509)
Perspective is called the bridle and the rudder of painting. The size of a painted figure should show at what distance it is seen: a figure shown life-size declares itself to be near the eye. A small perspective diagram accompanies the precept.