Nature is full of infinite causes that have never occurred in experience.

Whatever you do in life, if you want to be creative and intelligent, and develop your brain, you must do everything with the awareness that everything, in some way, connects to everything else.

Many will think they may reasonably blame me by alleging that my proofs are opposed to the authority of certain men held in the highest reverence by their inexperienced judgments; not considering that my works are the issue of pure and simple experience.

Make your work to be in keeping with your purpose

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.

The good painter must paint two things: a person and the essence of his soul.

Fire destroys falsehood, that is sophistry, and restores truth, driving out darkness.