A bird is an instrument working according to mathematical law, which instrument it is within the capacity of man to reproduce with all its movements.

The limiting surface of one thing is the beginning of another.

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.

The first of all simple colours is White ... We shall set down White for the representative of light, without which no colour can be seen; Yellow for the earth; Green for water; Blue for air; Red for fire; and Black for total darkness.

I'm not contented to capture the world. I want to change it.

He who is fixed to a star does not change his mind.

The eye is the window of the human body through which it feels its way and enjoys the beauty of the world.