First Causes Are Outside The Realm Of

Progress Is Achieved By Exchanging Our Theories For New Ones Which Go Further Than The Old, Until We Find One Based On A Larger Number Of Facts. ... Theories Are Only Hypotheses, Verified By More Or Less Numerous Facts. Those Verified By The Most Facts Are The Best, But Even Then They Are Never Final, Never To Be Absolutely Believed.

The Physiologist Is Not A Man Of The World, He Is A Scientist, A Man Caught And Absorbed By A Scientific Idea That He Pursues; He No Longer Hears The Cries Of The Animals, No Longer Sees The Flowing Blood, He Sees Only His Idea: Organisms That Hide From Him Problems That He Wants To Discover. He Doesn't Feel That He Is In A Horrible Carnage; Under The Influence Of A Scientific Idea, He Pursues With Delight A Nervous Filament Inside Stinking And Livid Flesh That For Any Other Person Would Be An Object Of Disgust And Horror.

In The Philosophic Sense, Observation Shows And Experiment Teaches.

The Investigator Should Have A Robust Faith - And Yet Not Believe.

Men Who Have Excessive Faith In Their Theories ... Make Poor Observations, Because They Choose Among The Results Of Their Experiments Only What Suits Their Object, Neglecting Whatever Is Unrelated To It And Carefully Setting Aside Everything Which Might Tend Toward The Idea They Wish To Combat