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Do Not Put Forward Anything That You Cannot Prove By Experimentation.
-Louis Pasteur
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Do Not Put Forward

Louis Pasteur
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Do Not Put Forward Anything That You Cannot Prove By Experimentation.

Understanding the Quote: "do not put forward anything that you cannot prove by experimentation...."

This quote by Louis Pasteur reflects deeply on the theme of prove. It connects to the universal human journey of purpose, motivation, and reflection. Often categorized under Prove, Experimentation, the quote offers insight, emotional clarity, and intellectual inspiration to readers worldwide.

Whether you’re a student exploring new ideas, a leader trying to motivate your team, or someone seeking direction in life — this quote provides value. It resonates because it’s more than words — it’s a bridge between experience and wisdom. It shows how Louis Pasteur interprets life's core challenges and triumphs.

Lessons From the Quote

This quote teaches resilience and focus. It reminds readers that no matter where they stand in life, reflection and self-awareness lead to growth. Each word has meaning, and when studied, it becomes clear how impactful thoughtful language can be.

About Louis Pasteur

Louis Pasteur is celebrated for insightful thoughts on prove and experimentation. Their legacy lives on through writings that guide, comfort, and inspire. Discover more on their profile page.

Actionable Takeaways

  • Reflect on how this quote applies to your current life path.
  • Share the message with someone who needs inspiration.
  • Write your thoughts on this quote in a journal or blog post.
  • Use it as a daily affirmation or reminder.

Closing Thoughts

Quotes like this endure because they capture universal truths. They comfort us in solitude and empower us in groups. Carry this quote forward — live by its wisdom, share its message, and keep its essence alive.

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Topic
Prove
Experimentation
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It Is A Matter Of Fact; I Approached Without A Preconceived Idea, Too Ready To Declare, If The Experiment Had Imposed Upon Me The Confession, That There Was A Spontaneous Generation, Of Which I Am Convinced Today That Those Who Assure It Are Blindfolded.
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There Is A Time In Every Man's Life When He Looks To His God, When He Looks At His Life, When He Wonders How He Will Be Remembered.
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In That Memorable Year, 1822: Oersted, A Danish Physicist, Held In His Hands A Piece Of Copper Wire, Joined By Its Extremities To The Two Poles Of A Volta Pile. On His Table Was A Magnetized Needle On Its Pivot, And He Suddenly Saw (by Chance You Will Say, But Chance Only Favours The Mind Which Is Prepared) The Needle Move And Take Up A Position Quite Different From The One Assigned To It By Terrestrial Magnetism. A Wire Carrying An Electric Current Deviates A Magnetized Needle From Its Position. That, Gentlemen, Was The Birth Of The Modern Telegraph.
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The Flavor Of Wine Is Like Delicate Poetry.
Wine
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The Role Of The Infinitely Small In Nature Is Infinitely Great.
Roles
One Must Not Assume That An Understanding Of Science Is Present In Those Who Borrow The Language
Understanding
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How Do You Know That The Incessant Progress Of Science Will Not Compel Scientists To Consider That Life Has Existed During Eternity, And Not Matter?
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Let Me Tell You The Secret That Has Led Me To My Goal. My Strength Lies Solely In My Tenacity.
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Time Is The Best Appraiser Of Scientific Work, And I Am Aware That An Industrial Discovery Rarely Produces All Its Fruit In The Hands Of Its First Inventor.
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We Affirm The Neutrality Of Science ... Science Is Of No Country. ... But If Science Has No Country, The Scientist Must Keep In Mind All That May Work Towards The Glory Of His Country. In Every Great Scientist Will Be Found A Great Patriot.
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The More I Know, The More Nearly Is My Faith That Of The Breton Peasant. Could I But Know All I Would Have The Faith Of A Breton Peasant Woman.
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If Perchance You Should Falter During The Journey, A Hand Would Be There To Support You. If That Should Be Wanting, God, Who Alone Could Take That Hand From You, Would Himself Accomplish Its Work.
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Great Problems Are Now Being Handled, Keeping Every Thinking Man In Suspense; The Unity Or Multiplicity Of Human Races; The Creation Of Man 1,000 Years Or 1,000 Centuries Ago; The Fixity Of Species, Or The Slow And Progressive Transformation Of One Species Into Another; The Eternity Of Matter; The Idea Of A God Unnecessary: Such Are Some Of The Questions That Humanity Discusses Nowadays.
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Messieurs, C'est Les Microbes Qui Auront Le Dernier Mot." (gentlemen, It Is The Microbes Who Will Have The Last Word.)
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Science Belongs To No One Country.
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In Good Philosophy, The Word Cause Ought To Be Reserved To The Single Divine Impulse That Has Formed The Universe.
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Chance Favors The Prepared Mind.
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Every Chemical Substance, Whether Natural Or Artificial, Falls Into One Of Two Major Categories, According To The Spatial Characteristic Of Its Form. The Distinction Is Between Those Substances That Have A Plane Of Symmetry And Those That Do Not. The Former Belong To The Mineral, The Latter To The Living World.
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The Grandeur Of The Acts Of Men Are Measured By The Inspiration From Which They Spring. Happy Is He Who Bears A God Within.
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My Present And Most Fixed Opinion Regarding The Nature Of Alcoholic Fermentation Is This: The Chemical Act Of Fermentation Is Essentially A Phenomenon Correlative With A Vital Act, Beginning And Ending With The Latter. I Believe That There Is Never Any Alcoholic Fermentation Without Their Being Simultaneously The Organization, Development, Multiplication Of The Globules, Or The Pursued, Continued Life Of Globules Which Are Already Formed.
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Life Comes Only From Life.
The Universe Is Asymmetric.
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As In The Experimental Sciences, Truth Cannot Be Distinguished From Error As Long As Firm Principles Have Not Been Established Through The Rigorous Observation Of Facts.
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The More I Study Nature, The More I Stand Amazed At The Work Of The Creator. Science Brings Men Nearer To God.
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Without Theory, Practice Is But Routine Born Of Habit. Theory Alone Can Bring Forth And Develop The Spirit Of Inventions.
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Virulence Appears In A New Light Which Cannot But Be Alarming To Humanity; Unless Nature, In Her Evolution Down The Ages (an Evolution Which, As We Now Know, Has Been Going On For Millions, Nay, Hundreds Of Millions Of Years), Has Finally Exhausted All The Possibilities Of Producing Virulent Or Contagious Diseases - Which Does Not Seem Very Likely.
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Posterity Will One Day Laugh At The Foolishness Of Modern Materialistic Philosophers.
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The Artificial Products Do Not Have Any Molecular Dissymmetry; And I Could Not Indicate The Existence Of A More Profound Separation Between The Products Born Under The Influence Of Life And All The Others.
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Worship The Spirit Of Criticism. If Reduced To Itself It Is Not An Awakener Of Ideas Or A Stimulant To Great Things, But, Without It, Everything Is Fallible; It Always Has The Last Word.
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La Fortuna Juega A Favor De Una Mente Preparada
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To Demonstrate Experimentally That A Microscopic Organism Actually Is The Cause Of A Disease And The Agent Of Contagion, I Know No Other Way, In The Present State Of Science, Than To Subject The Microbe (the New And Happy Term Introduced By M. Sédillot) To The Method Of Cultivation Out Of The Body.
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These Are The Living Springs Of Great Thoughts And Great Actions. Everything Grows Clear In The Reflections From The Infinite.
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Science And Peace Will Triumph Over Ignorance And War...
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Imagination Should Give Wings To Our Thoughts But We Always Need Decisive Experimental Proof, And When The Moment Comes To Draw Conclusions And To Interpret The Gathered Observations, Imagination Must Be Checked And Documented By The Factual Results Of The Experiment.
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Science Knows No Country Because It Is The Light That Iluminates The World
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My Opinion - Nay More, My Conviction - Is That, In The Present State Of Science, As You Rightly Say, Spontaneous Generation Is A Chimera; And It Would Be Impossible For You To Contradict Me, For My Experiments All Stand Forth To Prove That Spontaneous Generation Is A Chimera.
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When One Works And Imagines And Dreams Of Nothing Else Than The Search For Answers That God Has Posed, It Is Difficult To Be So Still.
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No, There Is Now No Circumstance Known In Which It Can Be Affirmed That Microscopic Beings Came Into The World Without Germs, Without Parents Similar To Themselves. Those Who Affirm It Have Been Duped By Illusions, By Ill-conducted Experiments, Spoilt By Errors That They Either Did Not Perceive Or Did Not Know How To Avoid.
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These Microscopic Organisms Form An Entire World Composed Of Species, Families And Varieties Whose History, Which Has Barely Begun To Be Written, Is Already Fertile In Prospects And Findings Of The Highest Importance. The Names Of These Organisms Are Very Numerous And Will Have To Be Defined And In Part Discarded. The Word Microbe Which Has The Advantage Of Being Shorter And Carrying A More General Meaning, And Of Having Been Approved By My Illustrious Friend, M. Littré, The Most Competent Linguist In France, Is One We Will Adopt.
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Question Your Priorities Often, Make Sure God Always Comes First.
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Luck Favors The Mind That Is Prepared.
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I Have The Faith Of A Breton Peasant And By The Time I Die I Hope To Have The Faith Of A Breton Peasant's Wife.
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Nothing Is Lost And Nothing Is Created In The Operations Of Art As Those Of Nature.
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Chance Favours The Trained Mind.
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Since The Most Ancient Times, All Men, And Particularly Those Who Endeavored In The Practice Of Medicine, Have Brought Closer Together Two Natural Phenomena Of Capital Importance: Illness Or Fever And Fermentation.
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Preconceived Ideas Are Like Searchlights Which Illumine The Path Of The Experimenter And Serve Him As A Guide To Interrogate Nature. They Become A Danger Only If He Transforms Them Into Fixed Ideas-this Is Why I Should Like To See These Profound Words Inscribed On The Threshold Of All The Temples Of Science: 'the Greatest Derangement Of The Mind Is To Believe In Something Because One Wishes It To Be So.'
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To Bring One's Self To Believe In A Truth That Has Just Dawned Upon One Is The First Step Towards Progress; To Persuade Others Is The Second.
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God Grant That By My Persevering Labours I May Bring A Little Stone To The Frail And Ill-assured Edifice Of Our Knowledge Of Those Deep Mysteries Of Life And Death Where All Our Intellects Have So Lamentably Failed.
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The Universe Is An Asymmetrical Entity. I Am Inclined To Believe That Life As It Is Manifested To Us Must Be A Function Of The Asymmetry Of The Universe Or Of The Consequence Of This Fact. The Universe Is Asymmetrical; For If One Placed The Entire Set Of Bodies That Compose The Solar System, Each Moving In Its Own Way, Before A Mirror, The Image Shown Would Not Be Superimposable On The Reality.
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If You Suppress Laboratories, Physical Science Will Be Stricken With Barrenness And Death.
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After Death, Life Reappears In A Different Form And With Different Laws. It Is Inscribed In The Laws Of The Permanence Of Life On The Surface Of The Earth And Everything That Has Been A Plant And An Animal Will Be Destroyed And Transformed Into A Gaseous, Volatile And Mineral Substance.
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To Know How To Wonder And Question Is The First Step Of The Mind Toward Discovery.
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Do Not Let Yourself Be Tainted With A Barren Skepticism.
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Live In The Serene Peace Of Laboratories And Libraries
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Intuition Is Given Only To Him Who Has Undergone Long Preparation To Receive It.
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There Are No Such Things As Applied Sciences, Only Applications Of Science.
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When You Believe You Have Found An Important Scientific Fact, And Are Feverishly Curious To Publish It, Constrain Yourself For Days, Weeks, Years Sometimes, Fight Yourself, Try And Ruin Your Own Experiments, And Only Proclaim Your Discovery After Having Exhausted All Contrary Hypotheses. But When, After So Many Efforts You Have At Last Arrived At A Certainty, Your Joy Is One Of The Greatest Which Can Be Felt By A Human Soul.
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Do Not Promote What You Can't Explain, Simplify, And Prove Early.
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Oh My Goodness The Mystery That Has Prompted My Objective. My Quality Lies Exclusively In My Tirelessness.
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Posterity Will One Day Laugh At The Sublime Foolishness Of The Modern Materialistic Philosophy. The More I Study Nature, The More I Stand Amazed At The Work Of The Creator. I Pray While I Am Engaged At My Work In The Laboratory.
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There Is No Such Thing As Applied Science, Only The Application Of Pure Science.
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My Strength Lies Solely In My Tenacity.
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In The Realm Of Scientific Observation, Luck Is Granted Only To Those Who Are Prepared.
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The Greatest Disorder Of The Mind Is To Let Will Direct It.
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The Greeks Understood The Mysterious Power Of The Below Things. They Are The Ones Who Gave Us One Of The Most Beautiful Words In Our Language, The Word Enthusiasm.
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I Propose To Provide Proof... That Just As Always An Alcoholic Ferment, The Yeast Of Beer, Is Found Where Sugar Is Converted Into Alcohol And Carbonic Acid, So Always A Special Ferment, A Lactic Yeast, Is Found Where Sugar Is Transformed Into Lactic Acid. And, Furthermore, When Any Plastic Nitrogenated Substance Is Able To Transform Sugar Into That Acid, The Reason Is That It Is A Suitable Nutrient For The Growth Of The [lactic] Ferment.
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Will Opens The Door To Success, Both Brilliant And Happy.
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Analogy Cannot Serve As Proof.
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One Does Not Ask Of One Who Suffers: What Is Your Country And What Is Your Religion? One Merely Says: You Suffer, That Is Enough For Me.
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I Give Them Experiments And They Respond With Speeches.
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There Are Two Men In Each One Of Us: The Scientist, He Who Starts With A Clear Field And Desires To Rise To The Knowledge Of Nature Through Observations, Experimentation And Reasoning, And The Man Of Sentiment, The Man Of Belief, The Man Who Mourns His Dead Children, And Who Cannot, Alas, Prove That He Will See Them Again, But Who Believes That He Will, And Lives In The Hope – The Man Who Will Not Die Like A Vibrio, But Who Feels That The Force That Is Within Him Cannot Die.
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There Is No Such Thing As A Special Category Of Science Called Applied Science; There Is Science And Its Applications, Which Are Related To One Another As The Fruit Is Related To The Tree That Has Borne It.
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Where Are The Real Sources Of Human Dignity, Freedom And Modern Democracy, If Not In The Concept Of Infinity To Which All Men Are Equal?
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Herrmann Pidoux And Armand Trousseau Stated 'disease Exists Within Us, Because Of Us, And Through Us', Pasteur Did Not Entirely Disagree, 'this Is True For Certain Diseases', He Wrote Cautiously, Only To Add Immediately: 'i Do Not Think That It Is True For All Of Them'.
Truth
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The Only Thing That Can Bring Joy Is Work.
Hard Work
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Did You Ever Observe To Whom The Accidents Happen? Chance Favors Only The Prepared Mind.
Past
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There Does Not Exist A Category Of Science To Which One Can Give The Name Applied Science. There Are Sciences And The Applications Of Science, Bound Together As The Fruit Of The Tree Which Bears It.
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Wine Is The Most Healthful And Most Hygienic Of Beverages.
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Little Science Takes You Away From God But More Of It Takes You To Him.
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In Matters Of Observation Chance Favors Only The Prepared Mind. (not Literal Translation) - Dan's Les Champs De Observation Le Hasard Ne Favorise Que Les Esprits Prepares.
Life
Mind
Favors
Outsidetheir Laboratories, Thephysicianand Chemist Are Soldiers Without Arms On The Field Of Battle.
Soldier
Battle
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Whatever Your Career May Be, Do Not Let Yourselves Become Tainted By A Deprecating And Barren Scepticism.
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The Greatest Malfunction Of Spirit Is To Believe Things.
Believe
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You Have Not Succeeded In Your Experiments, That Is All There Is To It.
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These Three Things-work, Will, Success-fill Human Existences. Will Opens The Door To Success, Both Brilliant And Happy. Work Passes These Doors, And At The End Of The Journey Success Comes In To Crown One's Efforts.
Success
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The Universe Is Asymmetric And I Am Persuaded That Life, As It Is Known To Us, Is A Direct Result Of The Asymmetry Of The Universe Or Of Its Indirect Consequences. The Universe Is Asymmetric.
Life
Science
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A Bottle Of Wine Contains More Philosophy Than All The Books In The World.
Funny
Philosophy
Drinking
Chance Favours A Prepared Mind.
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Favour
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... By Chance You Will Say, But Chance Only Favors The Mind Which Is Prepared.
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Favors
Never Will The Doctrine Of Spontaneous Generation Recover From The Mortal Blow Struck By This Simple Experiment.
Blow
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Doctrine
If Science Has No Country, The Scientist Should Have One, And Ascribe To It The Influence Which His Works May Have In This World.
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The Greatest Derangement Of The Mind Is To Believe In Something Because One Wishes It To Be So.
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When I Approach A Child, He Inspires In Me Two Sentiments; Tenderness For What He Is, And Respect For What He May Become.
Respect
Teacher
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I Am On The Edge Of Mysteries And The Veil Is Getting Thinner And Thinner.
Veils
Mystery
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Chance Favors Those Who Are Prepared.
Wrestling
Favors
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Without Theory, Practice Is But Routine Born Of Habit. Theory Alone Can Bring Forth And Develop The Spirit Of Invention. ... [do Not] Share The Opinion Of Those Narrow Minds Who Disdain Everything In Science Which Has Not An Immediate Application. ... A Theoretical Discovery Has But The Merit Of Its Existence: It Awakens Hope, And That Is All. But Let It Be Cultivated, Let It Grow, And You Will See What It Will Become.
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The Grandeur Of The Acts Of Men Are Measured By The Inspiration From Which They Spring.
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Blessed Is He Who Carries Within Himself A God, An Ideal, And Who Obeys It: Ideal Of Art, Ideal Of Science, Ideal Of The Gospel Virtues, Therein Lie The Springs Of Great Thoughts And Great Actions; They All Reflect Light From The Infinite.
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Wine Is The Healthiest And Most Health-giving Of Drinks.
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Giving
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Work Usually Follows Will.
The Greeks Bequeathed To Us One Of The Most Beautiful Words In Our Language--the Word 'enthusiasm'--en Theos--a God Within. The Grandeur Of Human Actions Is Measured By The Inspiration From Which They Spring. Happy Is He Who Bears A God Within, And Who Obeys It.
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Spring
Inspiration
Where Observation Is Concerned, Chance Favors Only The Prepared Mind.
Life
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Science Advances Through Tentative Answers To A Series Of More And More Subtle Questions Which Reach Deeper And Deeper Into The Essence Of Natural Phenomena.
Essence
Answers
Natural
Science Proceeds By Successive Answers To Questions More And More Subtle, Coming Nearer And Nearer To The Very Essence Of Phenomena.
Essence
Answers
Subtle
The Controls Of Life Are Structured As Forms And Nuclear Arrangements, In A Relation With The Motions Of The Universe.
Astrology
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Worship The Spirit Of Criticism.
Criticism
Spirit
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It Would Seem To Me That I Was Committing A Theft If I Were To Let One Day Go By Without Doing Some Work.
One Day
Theft
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You Bring Me The Deepest Joy That Can Be Felt By A Man Whose Invincible Belief Is That Science And Peace Will Triumph Over Ignorance And War, That Nations Will Unite, Not To Destroy, But To Build, And That The Future Will Belong To Those Who Will Have Done Most For Suffering Humanity.
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The Nights Seem To Me Too Long... I Am Often Scolded By Madame Pasteur, But I Tell Her I Shall Lead Her To Fame.
Night
Long
Fame
Are The Atoms Of The Dextroacid (tartaric) Grouped In The Spirals Of A Right-hand Helix Or Situated At The Angles Of An Irregular Tetrahedron, Or Arranged In Such Or Such Particular Unsymmetrical Fashion? We Are Unable To Reply To These Questions. But There Can Be No Reason For Doubting That The Grouping Of The Atoms Has An Unsymmetrical Arrangement With A Non-superimposable Image. It Is Not Less Certain That The Atoms Of The Laevo-acid Realize Precisely An Unsymmetrical Arrangement Of The Inverse Of The Above.
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Hands
Doubt
Blessed Is He Who Carries Within Himself A God, An Ideal, And Obeys It.
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Ideals
Science Knows No Country, Because Knowledge Belongs To Humanity, And Is The Torch Which Illuminates The World.
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It Is Surmounting Difficulties That Makes Heroes.
Motivational
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If It Is A Terrifying Thought That Life Is At The Mercy Of The Multiplication Of These Minute Bodies [microbes], It Is A Consoling Hope That Science Will Not Always Remain Powerless Before Such Enemies.
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Do Not Put Forward Anything That You Cannot Prove By Experimentation.
Prove
Experimentation
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