Da Vinci Notes #57 - Find Something Outside to Prove

 

How to measure the pyramid of vision.

 

As regards the point in the eye; it is made more intelligible by

this: If you look into the eye of another person you will see your

own image.

 

Now imagine 2 lines starting from your ears and going to the

ears of that image which you see in the other man's eye; you

will understand that these lines converge in such a way that they

would meet in a point a little way beyond your own image mirrored in

the eye. And if you want to measure the diminution of the pyramid in

the air which occupies the space between the object seen and the

eye, you must do it according to the diagram figured below.

 

Let _mn_ be a tower, and _e f_ a, rod, which you must move backwards

and forwards till its ends correspond with those of the tower; then

bring it nearer to the eye, at _c d_and you will see that the image of

the tower seems smaller, as at _ro_. Then [again] bring it closer to

the eye and you will see the rod project far beyond the image of

the tower from _a_ to _b_ and from _t_ to _b_, and so you will

discern that, a little farther within, the lines must converge in a point.

 

 

Keith's Ideas:

1. To prove something which can't be proved from inside, find

    something from outside!

2. If you can't prove something by evidences, use deduction or

    induction.

 

 

Keith To

www.keithto.ws