On July 5th 1687, Sir Isaac Newton published his masterpiece the Philosophiæ Naturalis Principia Mathematica, one of the most important books ever written. The Principia is commonly thought to be the height scientific expression. It set off the mathematization of the physical sciences in a unified comprehensive work that saw the development of modern physics and modern science. It accomplished the first great unification in physics, a unified empirically based quantitative theory of nature that bridged the laws of motion, universal gravitation, and celestial mechanics. Newton's great admirer and friend, the astronomer Edmond Halley, saw the publication of the Principia as comparable to the establishment of society or the invention of writing.
Newton's Principia owes its genesis to a problem that had perplexed the best scientists of the day. Robert Hooke, Christopher Wren, and Edmond Halley had failed, in all their endeavours, to find a proof that a planet following the inverse square law (1/R^2) would orbit in an elliptical circle. Frustrated by the lack of progress regarding this persisting conundrum, Halley visited Newton in Cambridge to ask him about this very issue. Newton quickly answered Halley's question that a planet following inverse square gravitation would orbit in an ellipse and further astonished Halley greatly by answering that he had proved it many years ago during the time of the plague. Newton, however, had misplaced his paper but promised Halley that he would send him the proof in the intervening months. The work that Newton would then do, however, would not just stop at Halley's one question that Newton had already solved and forgotten about many years earlier. Rather, Halley's question would refocus Newton's interests onto science. Newton would take on previously unanswered questions on his part and develop them further plus reinstate results that he had, due to his highly reclusive nature, refused to divulge before. Halley was, absolutely, awestruck by the correspondences that Newton would send him in the next few months and by unrestrained genius of Newton's intellect that uncovered so many secrets of nature that only Newton had so far known, owing to his refusal to publish. Halley pleaded with Newton to publish his work, reasoning that his precedence might be threatened by other scientists who wished to publish. Halley further offered to proofread the book and fund its publication out of his own pocket. The result of Halley's prodding would lead to Newton working on the Principia. Newton would work day and night for a period 18 months that he would devote, with prodigious exclusivity, to the publication of the Principia. It is said Newton worked 20 hours a day, 7 days a week, slept 2-3 hours a day, and skipped most of his meals while writing the Principia. He communicated with almost nobody and was hardly ever seen in public.
The result was a work of science of superhuman caliber, a masterwork that provided precise mathematical descriptions of the entire workings of nature. It explained the motion of planets, the causes of tides, the precession of the equinoxes, the motion of projectiles, fluid mechanics, motion in vacuums, pendulums, elasticity, the orbits of comets, the orbits of the moons of Jupiter and Saturn, the spherical shapes of the Sun, the planets, and the moons, the oblate shape of the Earth, the equatorial bulge of the Earth's rotation and, in particular, how it derives from the gravitational forces of the moon, the physics of sounds and waves, plus many other natural phenomena. The Principia also explained how to calculate the mass of the Earth and the Sun and derived Kepler's laws of planetary motion from universal gravitation. All of this was cast in the language of Euclidean geometry, making the Principia a book of extremely complex geometrical proofs that even contemporary mathematicians, well versed in Greek geometry, struggled to understand. It was thought by contemporary mathematicians that the amount of novel mathematical work and mathematical research in the Principia exceeded the combined mathematical abilities of the human race. It was unthinkable to believe that all of this could be done by a singular effort. The great 20th century Nobel physicist Subrahmanyan Chrandrasekhar, in his study of the Principia, remarked that whenever he constructed the proofs on his own and then compared them to Newton's, he "felt like a schoolboy, admonished by his master".
Not only did the Principia revolutionize our understanding of the universe but it led to an era of reasoned thought that drew greatly from Newton's work and contributed the scientific revolution which permeated much of the Age of Enlightenment.
I'm so gobsmacked that I can't quite get my head around this.
Taken from an Imgur contributor.