Just As Houses Are Made Of Stones,

Often When Works At A Hard Question, Nothing Good Is Accomplished At The First Attack. Then One Takes A Rest, Long Or Short, And Sits Down Anew To The Work. During The First Half-hour, As Before, Nothing Is Found, And Then All Of A Sudden The Decisive Idea Presents Itself To The Mind.

Ideas Rose In Clouds; I Felt Them Collide Until Pairs Interlocked, So To Speak, Making A Stable Combination.

In One Word, To Draw The Rule From Experience, One Must Generalize; This Is A Necessity That Imposes Itself On The Most Circumspect Observer.

I Then Began To Study Arithmetical Questions Without Any Great Apparent Result, And Without Suspecting That They Could Have The Least Connexion With My Previous Researches. Disgusted At My Want Of Success, I Went Away To Spend A Few Days At The Seaside, And Thought Of Entirely Different Things. One Day, As I Was Walking On The Cliff, The Idea Came To Me, Again With The Same Characteristics Of Conciseness, Suddenness, And Immediate Certainty, That Arithmetical Transformations Of Indefinite Ternary Quadratic Forms Are Identical With Those Of Non-euclidian Geometry.

When The Logician Has Resolved Each Demonstration Into A Host Of Elementary Operations, All Of Them Correct, He Will Not Yet Be In Possession Of The Whole Reality, That Indefinable Something That Constitutes The Unity ... Now Pure Logic Cannot Give Us This View Of The Whole; It Is To Intuition That We Must Look For It.