Those who fall in love with practice without science are like a sailor who enters a ship without a helm or a compass, and who never can be certain whither he is going.

You don't get into trouble because of the things you don't know. It is the things you don't know you don't know that really get you into a mess.

Nothing will be left, Nothing in the air, nothing under the earth, nothing in the waters. All will be exterminated.

The variety of colour in objects cannot be discerned at a great distance, excepting in those parts which are directly lighted up by the solar rays.

How painting surpasses all human works by reason of the subtle possibilities which it contains.

I am not to blame for putting forward, in the course of my work on science, any general rule derived from a previous conclusion.

Just as courage imperils life, fear protects it.