Da Vinci Notes #51 - Seeing One Thing at a Time

 

IN WHAT WAY THE EYE SEES OBJECTS PLACED IN FRONT
OF IT.

 

The perception of the object depends on the direction of the eye.

 

Supposing that the ball figured above is the ball of the eye and let

the small portion of the ball which is cut off by the line _s t_ be

the pupil and all the objects mirrored on the centre of the face of

the eye, by means of the pupil, pass on at once and enter the pupil,

passing through the crystalline humour, which does not interfere in

the pupil with the things seen by means of the light. And the pupil

having received the objects, by means of the light, immediately

refers them and transmits them to the intellect by the line _a b_.

 

And you must know that the pupil transmits nothing perfectly to the

intellect or common sense excepting when the objects presented to it

by means of light, reach it by the line _a b;_ as, for instance, by

the line _b c_. For although the lines _m n_ and _f g_ may be seen

by the pupil they are not perfectly taken in, because they do not

coincide with the line _a b_. And the proof is this: If the eye,

shown above, wants to count the letters placed in front, the eye

will be obliged to turn from letter to letter, because it cannot

discern them unless they lie in the line _a b;_ as, for instance, in

the line _a c_. All visible objects reach the eye by the lines of a

pyramid, and the point of the pyramid is the apex and centre of it,