Hypotheses Non Fingo. I Frame No Hypotheses.

Thus Far I Have Explained The Phenomena Of The Heavens And Of Our Sea By The Force Of Gravity, But I Have Not Yet Assigned A Cause To Gravity. Indeed, This Force Arises From Some Cause That Penetrates As Far As The Centers Of The Sun And Planets Without Any Diminution Of Its Power To Act, And That Acts Not In Proportion To The Quantity Of The Surfaces Of The Particles On Which It Acts (as Mechanical Causes Are Wont To Do) But In Proportion To The Quantity Of Solid Matter, And Whose Action Is Extended Everywhere To Immense Distances, Always Decreasing As The Squares Of The Distances.

When Two Forces Unite, Their Efficiency Double.

Do Not The Rays Of Light Which Fall Upon Bodies, And Are Reflected Or Refracted, Begin To Bend Before They Arrive At The Bodies; And Are They Not Reflected, Refracted, And Inflected, By One And The Same Principle, Acting Variously In Various Circumstances?

The Best Way To Understanding Is A Few Good Examples.

Doth Not This Æthereal Medium In Passing Out Of Water, Glass, Crystal, And Other Compact And Dense Bodies Into Empty Spaces, Grow Denser And Denser By Degrees, And By That Means Refract The Rays Of Light Not In A Point, But By Bending Them Gradually In Curve Lines? And Doth Not The Gradual Condensation Of This Medium Extend To Some Distance From The Bodies, And Thereby Cause The Inflexions Of The Rays Of Light, Which Pass By The Edges Of Dense Bodies, At Some Distance From The Bodies?