It Is... Easy To Be Certain. One

The Difference Between A Pessimistic And An Optimistic Mind Is Of Such Controlling Importance In Regard To Every Intellectual Function, And Especially For The Conduct Of Life, That It Is Out Of The Question To Admit That Both Are Normal, And The Great Majority Of Mankind Are Naturally Optimistic.

Doubt Is An Uneasy And Dissatisfied State From Which We Struggle To Free Ourselves And Pass Into The State Of Belief; While The Latter Is A Calm And Satisfactory State Which We Do Not Wish To Avoid, Or To Change To A Belief In Anything Else.

It Is A Common Observation That A Science First Begins To Be Exact When It Is Quantitatively Treated. What Are Called The Exact Sciences Are No Others Than The Mathematical Ones.

Effort Supposes Resistance.

It Is Terrible To See How A Single Unclear Idea, A Single Formula Without Meaning, Lurking In A Young Man's Head, Will Sometimes Act Like An Obstruction Of Inert Matter In An Artery, Hindering The Nutrition Of The Brain And Condemning Its Victim To Pine Away In The Fullness Of His Intellectual Vigor And In The Midst Of Intellectual Plenty.