As for movement of the heavenly body, the law was explained by Kepler. However, Kepler's laws of planetary motion had three, and the law was a little complicated for considering it as the ultimate principles of a nature. Universal gravitation which Newton considered. If the law is right and is a more fundamental law, all of three laws of Kepler should be drawn from universal gravitation. As a result, it arrives at the idea that the power committed between two objects is decided by the mass of a substance, and distance between objects. If its mass is large, it is large, and if the strength of gravitation which works between two objects has a small distance, it is large.
Newton is writing the equation which describes quantitatively the strength of gravitation which works between two more objects. According to the equation, the attraction committed between two objects is proportional to the product of objective mass, and in inverse proportion to the square of distance. By this law of gravitation, it succeeded also in drawing three laws of Kepler.
It means discovery of a briefer and more fundamental law. This theory also comes to be called the general relativity which makes the special relativity of Einstein who talked to the second, and a pair.
