Geometry Is Not True, It Is Advantageous.

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.

Later Generations Will Regard Mengenlehre (set Theory) As A Disease From Which One Has Recovered.

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.

Consider Now The Milky Way. Here Also We See An Innumerable Dust, Only The Grains Of This Dust Are No Longer Atoms But Stars; These Grains Also Move With Great Velocities, They Act At A Distance One Upon Another, But This Action Is So Slight At Great Distances That Their Trajectories Are Rectilineal; Nevertheless, From Time To Time, Two Of Them May Come Near Enough Together To Be Deviated From Their Course, Like A Comet That Passed Too Close To Jupiter. In A Word, In The Eyes Of A Giant, To Whom Our Suns Were What Our Atoms Are To Us, The Milky Way Would Only Look Like A Bubble Of Gas.

One Does Not Ask Whether A Scientific Theory Is True, But Only Whether It Is Convenient.