Art is never finished, only abandoned. - Leonardo da Vinci

They will say that I, having no literary skill, cannot properly express that which I desire to treat of, but they do not know that my subjects are to be dealt with by experience rather than by words. And [experience] has been the mistress of those who wrote well. And so, as mistress, I will cite her in all cases. Though I may not, like them, be able to quote other authors, I shall rely on that which is much greater and more worthy: on experience, the mistress of their masters.

The sun gives spirit and life to plants and the earth nourishes them with moisture.

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.