Isaac Newton — "It is possible that gravity may be essential to matter."

"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."

"Every body continues in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed upon it."

"For the best and safest way of philosophizing seems to be, first to inquire diligently into the properties of things, and of establishing them by experiment, and then to proceed more slowly to hypothe…"

"The whole difficulty of philosophy seems to consist in this—from the phenomena of motions to investigate the forces of nature, and then from these forces to demonstrate the other phenomena."

"Nature is pleased with simplicity, and affects not the pomp of superfluous causes."