First Of All, We Must Note That

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

Mathemata Mathematicis Scribuntur Mathematics Is Written For Mathematicians De Revolutionibus

Therefore, In The Course Of The Work I Have Followed This Plan: I Describe In The First Book All The Positions Of The Orbits Together With The Movements Which I Ascribe To The Earth, In Order That This Book Might Contain, As It Were, The General Scheme Of The Universe.

First Of All, We Must Note That The Universe Is Spherical.

Therefore I Would Not Have It Unknown To Your Holiness, The The Only Thing Which Induced Me To Look For Another Way Of Reckoning The Movements Of The Heavenly Bodies Was That I Knew That Mathematicians By No Means Agree In Their Investigation Thereof.