Isaac Newton
Sir Isaac Newton (1643-1727) was an English mathematician, physicist, and astronomer, and one of the most influential scientists who ever lived. His work laid the foundations of classical mechanics, and his picture of the universe dominated science for more than two centuries.
In his masterpiece, the Principia (Philosophiae Naturalis Principia Mathematica, 1687), Newton set out his three laws of motion and the law of universal gravitation, showing that the same force that makes an apple fall also holds the planets in their orbits. In Opticks (1704) he explained the nature of light and colour, demonstrating that ordinary white light is made of a spectrum of colours.
Newton also made fundamental contributions to mathematics, developing the essentials of calculus independently of Leibniz, and he served as Master of the Royal Mint and President of the Royal Society. He was a complex figure who poured enormous energy into alchemy and theology alongside his scientific work.
His great works were written in the formal Latin and dense mathematical style of his age, which makes the originals forbidding for most readers. Our editions present his key writings and ideas in clearer modern English, so you can follow the reasoning that reshaped how humanity understands the physical world. Read a selection free, and read or listen with a membership.
Isaac Newton in the library · 2 works
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Frequently asked questions about Isaac Newton
What did Isaac Newton write?
Newton's two most important books are the Principia (1687), which lays out his laws of motion and universal gravitation, and Opticks (1704), on light and colour. He also wrote extensively on mathematics, theology, and alchemy, though those writings are far less widely read. The Principia is generally regarded as one of the most important scientific books ever published.
What is Isaac Newton best known for?
He is best known for formulating the law of universal gravitation and the three laws of motion, which together explained the movement of everything from falling objects to the planets. He is also credited with co-inventing calculus and with groundbreaking work on light and optics. The famous story of a falling apple prompting his thoughts on gravity comes from his own accounts, though it is often exaggerated.
What are Newton's three laws of motion?
In brief: an object stays at rest or in steady motion unless a force acts on it (inertia); force equals mass times acceleration; and for every action there is an equal and opposite reaction. These three principles, set out in the Principia, became the foundation of classical physics and are still taught today. They describe how forces govern motion across everyday and astronomical scales.
Is Newton's writing hard to read?
The originals are. The Principia was written in Latin and presented as formal geometry, and even period English translations are heavy going. The ideas underneath, however, can be explained clearly. Reading his key writings in modern English lets you follow the logic and significance without decoding 17th-century mathematical prose.
When did Isaac Newton live?
Newton was born in 1643 and died in 1727, living through the height of the Scientific Revolution in England. He published the Principia in 1687 and Opticks in 1704, and spent his later years in public office as Master of the Royal Mint. He was knighted in 1705 and is buried in Westminster Abbey.
Did Newton really invent calculus?
Newton developed the core ideas of calculus in the 1660s, independently of the German mathematician Gottfried Leibniz, who developed and published his own version slightly later. This led to one of the most famous priority disputes in the history of science. Today both are credited as independent co-inventors, though the notation used in schools mostly comes from Leibniz.
Where can I read Newton's works for free?
Newton's major works are in the public domain, and older English translations are freely available. They can be very difficult for a general reader, though. Here you can read a selection of his key writings free in clearer modern English, and read or listen with a membership.
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