First Of All, We Must

For I Am Not So Enamoured Of My Own Opinions That I Disregard What Others May Think Of Them.

In So Many And Such Important Ways, Then, Do The Planets Bear Witness To The Earth's Mobility.

Of All Things Visible, The Highest Is The Heaven Of The Fixed Stars.

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.

Yet The Widespread Planetary Theories, Advanced By Ptolemy And Most Other Astronomers, Although Consistent With The Numerical Data, Seemed Likewise To Present No Small Difficulty. For These Theories Were Not Adequate Unless They Also Conceived Certain Equalizing Circles, Which Made The Planet Appear To Move At All Times With Uniform Velocity Neither On Its Deferent Sphere Nor About Its Own Epicycle's Center.