He formulated the Law of Universal Gravitation, which states:

* Every particle of matter in the universe attracts every other particle with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

This means:

* The more massive the objects, the stronger the gravitational attraction.

* The closer the objects, the stronger the gravitational attraction.

This force of gravity is what keeps the planets orbiting the Sun, and it is also responsible for many other phenomena, like the tides and the moon's orbit around the Earth.