In the days of thy youth seek to obtain that which shall compensate the losses of thy old age. And if thou understandest that old age is fed with wis… - Leonardo da Vinci

If the Lord — who is the light of all things — vouchsafe to enlighten me, I will treat of Light; wherefore I will divide the present work into 3 Parts... Linear Perspective, The Perspective of Colour, The Perspective of Disappearance.

It is impossible that the eye should project from itself, by visual rays, the visual virtue, since, as soon as it opens, that front portion [of the eye] which would give rise to this emanation would have to go forth to the object and this it could not do without time. And this being so, it could not travel so high as the sun in a month's time when the eye wanted to see it.

Love, Fear, and Esteem, — Write these on three stones.