Nothing strengthens authority so much as silence.

Just as eating against one's will is injurious to health, so studying without a liking for it spoils the memory, and it retains nothing it takes in.

Perspective is a most subtle discovery in mathematical studies, for by means of lines it causes to appear distant that which is near, and large that which is small.

The Bactrian have two humps; the Arabian one only. They are swift in battle and most useful to carry burdens. This animal is extremely observant of rule and measure, for it will not move if it has a greater weight than it is used to, and if it is taken too far it does the same, and suddenly stops and so the merchants are obliged to lodge there.

Good writing comes from good talent.

It should not be hard for you to stop sometimes and look into the stains of walls, or ashes of a fire, or clouds, or mud or like places, in which...you may find really marvellous ideas.

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.