The window does the same on each side, both below and above and likewise on one side as on the other, where it borders on the dark wall.
And the same is done by the species that enter the pupil and are cast to right and left, intersected beyond the object set before it.

f e d c b – a - g f e d

b K a f L c o t – m n – S r q X p g [h]
o p sees and is seen by a b and is tinged with its colour, and on the side p it sees the beginning of the brightness of the air a c, which lights the place where its image strikes.
Why does black painted at the border of white not show more black than where it borders on black, nor does white show more white at the border of black than at the border of white, as do the species passed through an aperture or past the edge of some opaque obstacle?
This arises because the species tinge the place where they cut with their colour; and when unlike species see one same place, they make a mixture of their colours, which partakes more or less of one than of the other according as one colour is of greater quantity. And at their edges the colours are more intense and more distinct than elsewhere. It is proved by the fourth of this, which says: the surface of every opaque body partakes of the colour of its object. It follows that the line a p tinges the surface n p of itself, and this line carries with it the boundary of the light c a with the dark a b, and on this line it sees no part of the dark but all light. But if you move further from the boundary of the derivative shadow, then that brightness g h is tinged with the shadow a K, and thus the illuminated part is corrupted by the percussion or mixture of the shadowy image a K, which it could not do at m g p and especially at p. And thus our intent is proved, to show that the boundary of the bright image with the derivative shadow is brighter in fact, and not in appearance as the opponent wishes, than the remainder of the other field. It remains to prove why the boundary of the derivative shadow is darker at the border of the bright field than in any other of its parts. The same as the aforesaid: why is the beginning of the shadow more in m X than elsewhere? Because at m X it sees no part of light, as it sees at m X q, where it sees f a m light.

Why does the boundary of the derivative shadow remain intersected beyond the pyramid of maximum darkness, and why is such intersected shadow dark toward the angle of the shadowy pyramid and light on the outside?
First answer.
The outer boundary of the derivative shadow that intersects will be darker on the outside than toward the middle, because in n X, the further you move from X toward S, the more light you find in a l; and you find the contrary in the opposite part, because the further you move from p toward o, the more the darkness a b shows itself. And this is said as regards the field of the intersected derivative shadow.

K h o g i – f c – d q b e p a

* Why does a light make a pyramidal shadow behind the opaque body? Shadows are of 3 kinds of shape, of which the first is pyramidal, the second parallel, the third semi-pyramidal cuts ...
* Two shadows are made by a single light, because the whole light g h sees the whole space a b c, and on the other side it sees the space e d f; but in ...

e f d – p c r - h – o m b S n a

Why are shadows never similar to the opaque body, unless the light is equal and similar to the opaque body and is not stamped upon a flat wall between equal angles? Two shadows are made by a single light and a single object when the light is larger than the object. This is caused because the whole light d e lights the space d e r a, but the space c a b, at every degree that it approaches the line c b, always loses the sight of that light, as the motion of the line f n toward b shows, for the more n approaches b, the more, above, with its opposite end, f approaches d e and narrows the space of the light e d. In like manner is born the second shadow p n o; and the triangle S h b is wholly seen by the light d e, because the half of the light f e sees with its parts in S m and the other half d f sees with its parts in n b, but the triangle h S b is seen by both halves of that light d e, and because two halves make one whole.

e d c b a – K i h g f

* What drives the nail better — closer to the mouth of the hammer, or when it is separated?

a-cb

n f e d c b a - p o - g - v t S r q
In the triangle g r t it sees the triangle a c o, which is luminous, and also sees there the opposite luminous triangle e n p. Therefore in that triangle g r t it will be twice as luminous as in the two side triangles o g r and p g t, where its light, though of the same derivation, is simple, and the other is composed of two lights. Therefore this illuminated triangle is the one that separates the two shadows o p q r and o p t v one from the other.

h g f e d c b a - r q p o n m L K i
a d sees n r m, and the end of the light a sees in r and lights it little, because at the ends of lights there is little light; but in n it sees all the light a d, a simple light, so there is much light; m n sees a d light and d e shadow ...

Make in i r five spaces, or 9 or 7, so that the white n o stays in the middle.