Although human ingenuity may devise various inventions which, by the help of various instruments, answer to one and the same purpose, yet will it never discover any inventions more beautiful, more simple or more practical than those of nature, because in her inventions there is nothing lacking and nothing superfluous; and she makes use of no counterpoise when she constructs the limbs of animals in such a way as to correspond to the motion of their bodies, but she puts into them the soul of the body.

A heightened sense of the observation of nature is one of the chief delights that have come to me through trying to paint. I accumulated in those years so fine a surplus in the Book of Observance that I have been drawing confidently upon it ever since.

A bird as it rises always sets its wings above the wind and without beating them, and it always moves in a circular movement.

The frog instantly dies when the spinal cord is pierced; and previous to this it lived without head without heart or any bowels or intestines orskin; and here therefore it would seem lies the foundation of move- ment and life.

The air moves like a river and carries the clouds with it; just as running water carries all the things that float upon it.

To any white body receiving the light from the sun, or the air, the shadows will be of a bluish cast.