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.
Leonardo da VinciThe mind that engages in subjects of too great variety becomes confused and weakened.
Leonardo da VinciTrue and great love springs out of great knowledge, and where you know little you can love but little or not at all.
Leonardo da Vinci