Hypotheses Non Fingo. I Frame No Hypotheses.

I Have Presented Principles Of Philosophy That Are Not, However, Philosophical But Strictly Mathematical-that Is, Those On Which The Study Of Philosophy Can Be Based. These Principles Are The Laws And Conditions Of Motions And Of Forces, Which Especially Relate To Philosophy.

My Design In This Book Is Not To Explain The Properties Of Light By Hypotheses, But To Propose And Prove Them By Reason And Experiments: In Order To Which, I Shall Premise The Following Definitions And Axioms.

For The Rays, To Speak Properly, Have No Colour. In Them There Is Nothing Else Than A Certain Power And Disposition To Stir Up A Sensation Of This Colour Or That.

Absolute, True, And Mathematical Time, In And Of Itself And Of Its Own Nature, Without Reference To Anything External, Flows Uniformly And By Another Name Is Called Duration. Relative, Apparent, And Common Time Is Any Sensible And External Measure (precise Or Imprecise) Of Duration By Means Of Motion; Such As A Measure-for Example, An Hour, A Day, A Month, A Year-is Commonly Used Instead Of True Time.

He Who Thinks Half-heartedly Will Not Believe In God; But He Who Really Thinks Has To Believe In God.