The following article is part of a biography of Sir Isaac Newton, the English mathematician and scientist, author of the Principia. It portrays the years after Newton's birth in 1643, his education, as well as his early scientific contributions, before the writing of his main work, the Principia Mathematica, in 1685.

Sir Isaac Newton is known for many scientific findings. These discoveries include the laws of motion, the theory of gravity, and basic calculus. Although Newton was predominantly known for his discoveries in mathematics and physics, he also put much effort and study into chemistry, biblical history, and optics. One of Newton's most famous writings was the Principia where he described some of his major findings of time, physics, mathematics, and calculus. Although his theories soon became universal, he faced much opposition to his early theories. Specifically, his theory of gravity faced criticism from leading scientists such as Christiaan Huygens and Leibniz. After a few years of debate, Newton's concept of gravity became universally accepted as he became the dominant figure in the European continent.

Isaac Newton was born 25 December 1642 Old Style (4 January 1643 on the Gregorian calendar, which is now used) at Woolsthorpe Manor in Woolsthorpe-by-Colsterworth, a hamlet in the county of Lincolnshire. (At the time of Newton's birth, England had not adopted the Gregorian calendar and therefore his date of birth was recorded as 25 December, according to the Julian calendar.)

Newton was born three months after the death of his father, a prosperous farmer also named Isaac Newton. His father was described as a "wealthy and uneducated man". Born prematurely, young Isaac was a small child; his mother Hannah Ayscough reportedly said that he could have fit inside a quart mug. When Newton was three, his mother remarried and went to live with her new husband, the Reverend Barnabas Smith, leaving her son in the care of his maternal grandmother, Margery Ayscough. The young Isaac disliked his stepfather and held some enmity towards his mother for marrying him, as revealed by this entry in a list of sins committed up to the age of 19: "Threatening my father and mother to burn them and the house over them." Later on his mother returned after her husband died.

From age 12 to age 16, Newton resided with William Clarke, apothecary, in Grantham, where he acquired his interest in chemistry. While living with the Clarke family, Newton was educated at the free grammar school (where his signature can still be seen upon a library window sill). He spent much of his time on independent pursuits, and did poorly in school.^{[better source needed]} Newton was also captivated with mechanical devices and drawing. Not only did he analyze drawings and machines, he actually constructed them himself. From windmills to clocks, Newton constructed models of many objects that surrounded him in his everyday life. He was removed from school, and by October 1659 he was to be found at Woolsthorpe-by-Colsterworth, where his mother, widowed by now for a second time, attempted to make a farmer of him, which he hated. Henry Stokes, master at the King's School, persuaded his mother to send him back to school so that he might complete his education. Newton's uncle also had an influence in persuading his mother to send him back to school as he could see the natural ability of Isaac. This he did at the age of eighteen, achieving an admirable final report.

Newton lived his childhood during some of the most turbulent times in England as the Civil War began in 1642. Although the effects of the country's issues may not have directly affected Newton, the school and universities in England were certainly impacted. Whether it was for the better or worse was to be determined, but Newton was certainly going to have a unique schooling due to the country's unbalance.

Manuscript evidence shows that Newton's earliest known piece writing, a Latin phrasebook, as well as the first letter in his hand which has yet been found, addressed to a ‘Loving friend’, were copied from an unpublished version of a work on Latin pedagogy by William Walker, a schoolmaster and rector whose acquaintance with Newton is documented from 1665. This suggests an early influence of the schoolmaster on the natural philosopher when he was still a schoolboy.

In June 1661, he was admitted to Trinity College, Cambridge as a sizar—a sort of work-study role. At that time, the college's teachings were based on those of Aristotle, whom Newton supplemented with modern philosophers such as Descartes and astronomers such as Copernicus, Galileo, and Kepler. In 1665, he discovered the generalised binomial theorem and began to develop a mathematical theory that later became infinitesimal calculus. Soon after Newton had obtained his degree in August 1665, the university closed down as a precaution against the Great Plague of London. Although he had been undistinguished as a Cambridge student, Newton's private studies at his home in Woolsthorpe over the next two years saw the development of his theories on calculus, optics and the law of gravitation. In 1667 he returned to Cambridge as a fellow of Trinity.