Science Proceeds More By What

See Now The Power Of Truth.

It Was Granted To Me Alone To Discover All The New Phenomena In The Sky And Nothing To Anybody Else. This Is The Truth Which Neither Envy Nor Malice Can Supress.

But What Exceeds All Wonders, I Have Discovered Four New Planets And Observed Their Proper And Particular Motions, Different Among Themselves And From The Motions Of All The Other Stars; And These New Planets Move About Another Very Large Star [jupiter] Like Venus And Mercury, And Perchance The Other Known Planets, Move About The Sun. As Soon As This Tract, Which I Shall Send To All The Philosophers And Mathematicians As An Announcement, Is Finished, I Shall Send A Copy To The Most Serene Grand Duke, Together With An Excellent Spyglass, So That He Can Verify All These Truths.

I Would Beg The Wise And Learned Fathers (of The Church) To Consider With All Diligence The Difference Which Exists Between Matters Of Mere Opinion And Matters Of Demonstration. ... [i]t Is Not In The Power Of Professors Of The Demonstrative Sciences To Alter Their Opinions At Will, So As To Be Now Of One Way Of Thinking And Now Of Another. ... [d]emonstrated Conclusions About Things In Nature Of The Heavens, Do Not Admit Of Being Altered With The Same Ease As Opinions To What Is Permissible Or Not, Under A Contract, Mortgage, Or Bill Of Exchange.

If Experiments Are Performed Thousands Of Times At All Seasons And In Every Place Without Once Producing The Effects Mentioned By Your Philosophers, Poets, And Historians, This Will Mean Nothing And We Must Believe Their Words Rather Than Our Own Eyes?