Gravity explains the motions of the planets, but it cannot explain who sets the planets in motion.
Isaac NewtonThe Synthesis consists in assuming the Causes discovered and established as Principles, and by them explaining the Phรฆnomena proceeding from them, and proving the Explanations.
Isaac NewtonNow the smallest Particles of Matter may cohere by the strongest Attractions, and compose bigger Particles of weaker Virture.... There are therefore Agents in Nature able to make the Particles of Bodies stick together by very strong Attraction. And it is the Business of experimental Philosophy to find them out.
Isaac Newton