Aerial perspective: distant bodies dim and turn blue
With the soft forms of youth and sky-light falling on the head
A page of Leonardo's painting theory, headed by a ray diagram lettered f g h i K and a b c d e that measures how much open sky reaches each point of a head. The notes advise showing the young without muscles or sinews, only soft fleshiness, and explain how a vertical surface with an overhang is darker than the projecting face above it. The main argument is one of aerial perspective: at a distance the principal lights and shadows are consumed into a single middle shadow, so trees and other bodies grow darker, and the intervening air makes them brighten and turn blue, most in the shadows where colour is least true.
On this page
The quality of limbs according to age
On the quality of the limbs according to age, Leonardo directs that in the young one should not look for muscles or sinews. Instead they should be given soft fleshiness, with simple folds and roundness of limb.
How much sky reaches each point of the head (a–e)
Following the lettered diagram, Leonardo notes that at a no part of the sky f K illuminates it, at b the sky i K, at e the sky h K, at d the sky g K, and at e the sky f K entirely. From this he concludes that the breast will be of equal brightness to the forehead, nose and chin.
Distance confounds shadow and veils bodies in blue
Leonardo warns that with distance the principal lights and shadows are consumed and every quality is confounded into a single middle shadow, so that trees and every body look darker far off than near the eye. Beyond that darkness the interposed air makes the thing brighten and incline to blue. It turns blue sooner in the shadows than in the lit parts, where the truth of the colours shows itself more.
A body seen by more light shows brighter
A closing note states that a body will show itself the more illuminated the greater the sum of one same light by which it is seen. It ties brightness directly to the quantity of light reaching the surface.