This is because Newton refined Galileo's idea of inertia and created it as his first law of motion. Galileo stated that it was the propensity of things to resist changes in motion. Newton refined it by including: "Every thing continues in a condition of rest or uniform speed in a straight line except acted on by a nonzero net power".
Newton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses, and inversely proportional to the square of the distance between them. Newton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses, and inversely proportional to the square of the distance between them.
