<human>:  Who was the first person to discover the law of gravity?
<bot>: Isaac Newton was the first person to discover the law of gravity. In 1687, Newton published Philosophiæ Naturalis Principia Mathematica, which contained his theory of universal gravitation. This theory states that the gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.