Proportion of the Human Figure and Aerial Perspective
The three-braccia model, composing narrative scenes, and a city seen through mist
A page of painter's precepts opening with the proportion of the human figure: taking a man of three braccia as the mean, with the hand a third of a braccio that goes nine times into the body, as do the head and other intervals. It passes to the composition of narrative scenes, warning against showing every limb, and to enlarging a figure, and slips in a brief pyrotechnic note to distil sulphur and saltpetre. Two further passages, with a diagram of houses stepped up a slope and sight-lines converging on the eye, work out aerial perspective, how city buildings seen through mist appear lighter at their base and darker as they rise into thinner air.
On this page
The three-braccia man as the measure of proportion
Since a man of two braccia is small and one of four too large, the praiseworthy mean is three; the reader is told to measure many such men and take proportions from the best-formed. The hand is a third of a braccio and enters nine times into the body, as does the head, and the intervals from throat-pit to shoulder, shoulder to nipple, and between the nipples.
On composing narrative scenes
A precept warns against displaying every limb of the figures in a narrative, as those do who spoil the composition to show whole bodies. Figures set behind the first should be drawn entire, so their limbs appearing beyond the front figure keep their natural length and place. A heading on enlarging a figure follows.
Aerial perspective: a city seen through mist
The divisions between city houses are known by the lightening the mist makes low down: with the eye above the houses, the visual lines sink into thicker, less transparent air that appears whiter. Where houses differ in height, the truth is seen more in the thinner air, so buildings look darker the higher they rise.
Sight-lines through denser and thinner air
In a lettered diagram, n o p q are the qualities of air thick with vapours and a is the eye; house b c looks brighter at its base c because there the air is thicker. Though f is more distant than c it stands in thinner air, and the line of sight starting high sinks its end into lower, grosser air, so equal houses are told apart by the varied brightness of the mist.
A pyrotechnic note: distil sulphur and saltpetre
Interleaved among the painter's precepts is a terse heading, Fire, followed by the direction to distil sulphur and saltpetre, the ingredients of gunpowder. The note breaks off without a full recipe.