All our knowledge hast its origins in our perceptions … In nature there is no effect without a cause … Experience never errs; it is only your judgments that err by promising themselves effects such as are not caused by your experiments … Science is the observation of things possible, whether present or past; prescience is the knowledge of things which may come to pass.

King of the animals — as thou hast described him — I should rather say king of the beasts, thou being the greatest — because thou hast spared slaying them, in order that they may give thee their children for the benefit of the gullet, of which thou hast attempted to make a sepulchre for all animals; and I would say still more, if it were allowed me to speak the entire truth.

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

No human investigation can be called real science if it cannot be demonstrated mathematically.

He who possesses most must be most afraid of loss.

If you are representing a white body let it be surrounded by ample space, because as white has no colour of its own, it is tinged and altered in some degree by the colour of the objects surrounding it

A good painter has two main objects to paint, man and the intention of his soul. The former is easy, the latter hard as he has to represent it by the attitude and movement of the limbs.