<human>:  I have a question about the famous physicist Henry Isaac Newton. What was his most famous discovery?
<bot>: Newton’s most famous discovery was the law of gravity. This law states that every object in the universe attracts every other object with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. This law is the basis for the theory of universal gravitation, which is the foundation of modern physics.