Final answer:
Isaac Newton invented calculus to prove his idea of gravity, a significant advance that allowed him to mathematically express the motion of celestial bodies, which he presented in his work Principia Mathematica.
Step-by-step explanation:
To prove his idea of gravity, Sir Isaac Newton created calculus. Calculus is a branch of mathematics that he invented to express his concepts on the laws of motion and the gravitational force. Newton's formulation of gravitational force, alongside his other laws of motion, was compiled into his great work, the Philosophiae Naturalis Principia Mathematica, published in 1687. This work proposed a predictable and comprehensible framework for understanding not just terrestrial motion but also the celestial motions of planets and their satellites, using an exact mathematical form that could describe the orbits of heavenly bodies as conic sections, which include circles, ellipses, parabolas, and hyperbolas. Newton's law of gravity provided a major leap forward in the Scientific Revolution, building upon and advancing the studies of his predecessors and contemporaries such as Galileo Galilei, Robert Hooke, and others.