Sir Issac Newton, an English scientist & one of the most influential men in the human history was the first scientist ever to be knighted. Philosophiæ Naturalis Principia Mathematica was his work which was published in 1687 lay the groundwork for classical mechanics. His Universal gravitation and 3 laws of motion are the basis of mechanics for last 3 centuries. He was the one, who eradicated the last doubts about the heliocentrism and established coherency between his gravitational laws and Kepler’s laws of planetary motion. He is also known for building first practical reflecting telescope. He developed the theory of spectrum and formulated empirical law of cooling and studied the speed of sound.