"The parts of all homogeneal hard bodies which fully touch one another, stick together with a very strong attraction."

"The attractive force of the earth acts to the greatest distance, and is observed in the fall of the moon, which is continually drawn towards the earth."

"The description of right lines and circles, upon which geometry is founded, belongs to mechanics. Geometry does not teach us to draw these lines, but requires them to be drawn."

"No great discovery was ever made without a bold guess."

"The light which comes from the sun, and from all fire, consists of all the primary colours mixed together."