The college closed for 2 years due to the plague,
and Newton returned to his hometown of Woolsthorpe.
There he began work on developing new approaches to
mathematics, physics, and optics. He made the funda-
mental discovery that integration is the reverse process
of differentiation, and he used this unifying concept to
lay down the foundations for a general theory of calcu-
lus. (As such, he completed this work two decades
before German scholar G
OTTFRIED
W
ILHELM
L
EIBNIZ
(1646–1716) independently made the same discovery.)
Newton used the notion of a
FLUXION
(derivative) as
the basis of his approach. He summarized his work in
his 1671 piece De methodis serierum et fluxionum (The
method of infinite series and fluxions) but failed to have
the work published. (An English translation of the piece
was printed posthumously in 1736.) This seems to have
been a frequent problem for Newton. Historians gather
from examination of his letters and personal writings
that he had a morbid dislike and fear of criticism and
would invariably hold back from publishing his ideas.
This led to a bitter dispute, for instance, 20 years later
when Leibniz published his discoveries and claimed to
have invented calculus.
The University of Cambridge reopened in 1667,
and Newton returned to obtain a master’s degree 1
year later. By this time, through what he had shared
with friends and reported in letters, he had garnered a
reputation as a gifted scholar, and 2 years later, at the
352 Newton, Sir Isaac
Sir Isaac Newton, an eminent scientist of the 18th century, domi-
nated and revolutionized the mathematics and physics of the late
1600s and early 1700s. (Photo courtesy of the Science Museum,
London/Topham-HIP/The Image Works)
Considered the most important scientific work of modern times,
Sir Isaac Newton’s Principia outlines the inverse-square law of
gravitation and its application to the mathematical derivation
of Johannes Kepler’s three laws of planetary motion. (Photo
courtesy of the Science Museum, London/Topham-HIP/The
Image Works)