Isaac Newton — "To every action there is always opposed an equal reaction."

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

"The changing of bodies into light, and light into bodies, is very conformable to the course of nature, which seems delighted with transmutations."

"The best and safest method of philosophizing seems to be, first to inquire diligently into the properties of things, and to establish those properties by experiments, and then to proceed more slowly t…"

"I can calculate the motion of heavenly bodies, but not the madness of people."

"Gravity explains the motions of the planets, but it cannot explain who sets the planets in motion."