The Theory Must Not Contradict Empirical Facts.

Watch The Stars, And From Them Learn.

... Knowledge Must Continually Be Renewed By Ceaseless Effort, If It Is Not To Be Lost. It Resembles A Statue Of Marble Which Stands In The Desert And Is Continually Threatened With Burial By The Shifting Sand. The Hands Of Service Must Ever Be At Work, In Order That The Marble Continue To Lastingly Shine In The Sun. To These Serving Hands Mine Shall Also Belong.

The True Sign Of Intelligence Is Not Knowledge But Imagination.

The Measure Of Intelligence Is The Ability To Change.

Everything That Can Be Counted Does Not Necessarily Count; Everything That Counts Cannot Necessarily Be Counted.