The motions which the planets now have could not spring from any natural cause alone, but were impressed by an intelligent Agent.

The same thing is to be understood of all bodies, revolved in any orbits. They all endeavour to recede from the centres of their orbits, and were it not for the opposition of a contrary force which restrains them to and detains them in their orbits, which I therefore call Centripetal, would fly off in right lines with a uniform motion.

The proper method for inquiring after the properties of things is to deduce them from experiments.

Isaac Newton Quotes