Sir Isaac Newton is famous for formulating the laws of motion and gravity. In his seminal work, "Philosophiæ Naturalis Principia Mathematica," published in 1687, Newton laid the foundation for classical mechanics. He introduced three fundamental laws of motion that describe the relationship between a body and the forces acting upon it. His law of universal gravitation explains how all objects with mass are attracted to one another, a key principle that helps describe planetary motion and orbits. Newton's work significantly advanced our understanding of physics and laid the groundwork for future scientific discoveries and technologies.