First Of All, We Must Note That

To Know That We Know What We Know, And To Know That We Do Not Know What We Do Not Know, That Is True Knowledge.

I Shall Now Recall To Mind That The Motion Of The Heavenly Bodies Is Circular, Since The Motion Appropriate To A Sphere Is Rotation In A Circle.

I Can Easily Conceive, Most Holy Father, That As Soon As Some People Learn That In This Book Which I Have Written Concerning The Revolutions Of The Heavenly Bodies, I Ascribe Certain Motions To The Earth, They Will Cry Out At Once That I And My Theory Should Be Rejected.

In The Midst Of All Dwells The Sun. For Who Could Set This Luminary In Another Or Better Place In This Most Glorious Temple, Than Whence He Can At One And The Same Time Brighten The Whole.

The Strongest Affection And Utmost Zeal Should, I Think, Promote The Studies Concerned With The Most Beautiful Objects, Most Deserving To Be Known.