It Is By Logic We Prove. It

Just As Houses Are Made Of Stones, So Is Science Made Of Facts.

It Is With Logic That One Proves; It Is With Intuition That One Invents.

Thought Is Only A Flash Between Two Long Nights, But This Flash Is Everything.

How Is Error Possible In Mathematics?

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.