Philosophiæ Naturalis Principia Mathematica - Wikipedia

On July 5, 1687, Isaac Newton's great work Principia was published by Royal Society in England. It outlined his laws of motion and universal gravitation.
From the article:

"In the preface of the Principia, Newton wrote:[11]

[...] Rational Mechanics will be the sciences of motion resulting from any forces whatsoever, and of the forces required to produce any motion, accurately proposed and demonstrated [...] And therefore we offer this work as mathematical principles of his philosophy. For all the difficulty of philosophy seems to consist in this—from the phenomenas of motions to investigate the forces of Nature, and then from these forces to demonstrate the other phenomena [...]

The Principia deals primarily with massive bodies in motion, initially under a variety of conditions and hypothetical laws of force in both non-resisting and resisting media, thus offering criteria to decide, by observations, which laws of force are operating in phenomena that may be observed. It attempts to cover hypothetical or possible motions both of celestial bodies and of terrestrial projectiles. It explores difficult problems of motions perturbed by multiple attractive forces. Its third and final book deals with the interpretation of observations about the movements of planets and their satellites.

It shows:

how astronomical observations prove the inverse square law of gravitation (to an accuracy that was high by the standards of Newton's time);
offers estimates of relative masses for the known giant planets and for the Earth and the Sun;
defines the very slow motion of the Sun relative to the solar-system barycenter;
shows how the theory of gravity can account for irregularities in the motion of the Moon;
identifies the oblateness of the figure of the Earth;
accounts approximately for marine tides including phenomena of spring and neap tides by the perturbing (and varying) gravitational attractions of the Sun and Moon on the Earth's waters;
explains the precession of the equinoxes as an effect of the gravitational attraction of the Moon on the Earth's equatorial bulge; and
gives theoretical basis for numerous phenomena about comets and their elongated, near-parabolic orbits.
The opening sections of the Principia contain, in revised and extended form, nearly[12] all of the content of Newton's 1684 tract De motu corporum in gyrum.

The Principia begin with "Definitions"[13] and "Axioms or Laws of Motion",[14] and continues in three books."