The Doubter Is A True Man Of

A Fact In Itself Is Nothing. It Is Valuable Only For The Idea Attached To It, Or For The Proof Which It Furnishes.

Obervation Is A Passive Science, Experimentation Is An Active Science.

Real Science Exists, Then, Only From The Moment When A Phenomenon Is Accurately Defined As To Its Nature And Rigorously Determined In Relation To Its Material Conditions, That Is, When Its Law Is Known. Before That, We Have Only Groping And Empiricism.

Particular Facts Are Never Scientific; Only Generalization Can Establish Science.

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.