Just as a well-filled day brings blessed sleep, so a well-employed life brings a blessed death.
Leonardo da VinciAll 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 Vinci