Reversed pyramids and images seen upside down
Cut and reversed pyramids; the eye sees only by pyramid, and painters' perspective needs it
Continuing the doctrine of visual pyramids, this leaf treats what happens when a pyramid passes and strikes a body: at the intersection it throws back a new 'reversed' pyramid whose images appear upside down, smaller in proportion as the reversed pyramid is shorter than the straight one. In a dark place these reversed bases show the figure and colour of their cause inverted — the principle of the camera obscura. Leonardo closes with two axioms: the eye sees only by pyramid, and the perspective of painters has no place without the pyramid. The page is entirely text, written in a single column of mirror script.
On this page
Reversed pyramids invert the image in a dark place
As a pyramid passes and rubs the sides of the bodies before it, it makes an intersection and casts back a new reversed pyramid, whose images are rendered upside down and smaller as the reversed pyramid is shorter than the straight one. In a dark place these bases show the figure and colour of their cause inverted, and the eye itself sees only by pyramid.
Painters' perspective rests on the pyramid
Leonardo states as a governing axiom that the perspective of painters has no place without the pyramid. The whole apparatus of rays and pyramids described here is offered as the geometric ground on which pictorial perspective must stand.
Cutting a pyramid to find the size of its base
It may be possible, by the cut pyramids, to know the true magnitude of their base: if the angles of the cut equal those of the base, each base is proportional to the other as the length of the cut pyramid is to that of the whole. Where reversed pyramids intersect, their qualities are doubled.