Experiment Is The Sole Source Of Truth.

All That We Can Hope From These Inspirations, Which Are The Fruits Of Unconscious Work, Is To Obtain Points Of Departure For Such Calculations. As For The Calculations Themselves, They Must Be Made In The Second Period Of Conscious Work Which Follows The Inspiration, And In Which The Results Of The Inspiration Are Verified And The Consequences Deduced.‎

But All Of My Efforts Served Only To Make Me Better Acquainted With The Difficulty, Which In Itself Was Something.

The Advance Of Science Is Not Comparable To The Changes Of A City, Where Old Edifices Are Pitilessly Torn Down To Give Place To New, But To The Continuous Evolution Of Zoologic Types Which Develop Ceaselessly And End By Becoming Unrecognisable To The Common Sight, But Where An Expert Eye Finds Always Traces Of The Prior Work Of The Centuries Past. One Must Not Think Then That The Old-fashioned Theories Have Been Sterile And Vain.

Mathematics Has A Threefold Purpose. It Must Provide An Instrument For The Study Of Nature. But This Is Not All: It Has A Philosophical Purpose, And, I Daresay, An Aesthetic Purpose.

When The Physicists Ask Us For The Solution Of A Problem, It Is Not Drudgery That They Impose On Us, On The Contrary, It Is Us Who Owe Them Thanks.