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 judgmen… - Leonardo da Vinci

All our knowledge has its origin in our perceptions

All our knowledge has its origins in our perceptions.

All our knowledge has its origin in our perceptions.

Science is the observation of things possible, whether present or past; prescience is the knowledge of things which may come to pass, though but slowly.

Science, knowledge of the things that are possible present and past; prescience, knowledge of the things which may come to pass.

The air which is struck with most swiftness by the movable thing is compressed to the greatest degree in itself.

Those who are in love with practice without knowledge are like the sailor who gets into a ship without rudder or compass and who never can be certain whether he is going. Practice must always be founded on sound theory, and to this Perspective is the guide and the gateway; and without this nothing can be done well in the matter of drawing.

Nothing can be loved or hated unless it is first understood.