Therefore, Having Obtained The Opportunity From These

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.

We Are Taught All This [the Motion Of The Earth On Its Axis And Around The Sun] By The Order Of Succession, In Which Those Phenomena (various Planetary Happenings) Follow Each Other, And By The Harmony Of The World, If We Will Only, As The Saying Goes, Look At The Matter With Both Eyes.

Finally We Shall Place The Sun Himself At The Center Of The Universe.

Therefore, Having Obtained The Opportunity From These Sources, I Too Began To Consider The Mobility Of The Earth.

For It Is The Duty Of An Astronomer To Compose The History Of The Celestial Motions Through Careful And Expert Study.