Who would believe that so small a space could contain the images of all the universe?

The eye transmits its own image through the air to all the objects which face it, and also receives them on its own surface, whence the "sensus communis" takes them and considers them.

If you are on the side whence the wind is blowing you will see the trees looking much lighter than you would see them on the other sides; and this is due to the fact that the wind turns up the reverse side of the leaves which in all trees is much whiter than the upper side.

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

Nature is so delightful and abundant in its variations that there would not be one that resembles another, and not only plants as a whole, but among their branches, leaves and fruit, will not be found one which is precisely like another.

What induces you, oh man, to depart from your home in town, to leave parents and friends, and go to the countryside over mountains and valleys, if it is not for the beauty of the world of nature?

Weight is caused by one element being situated in another; and it moves by the shortest line towards its centre, not by its own choice, not because the centre draws it to itself, but because the other intervening element cannot withstand it.

To speak of this subject you must... explain the nature of the resistance of the air, in the second the anatomy of the bird and its wings, in the third the method of working the wings in their various movements, in the fourth the power of the wings and the tail when the wings are not being moved and when the wind is favourable to serve as guide in various movements.

Music may be called the sister of painting, for she is dependent upon hearing, the sense which comes second and her harmony is composed of the union of proportional parts sounded simultaneously, rising and falling in one or more harmonic rhythms.