Newton's great work - Philosophiae Naturalis Principia Mathematica - was not published until the 1680's. But Newton had already made most of his discoveries in relation to gravitation when a young man, newly appointed to the chair of mathematics at Cambridge University, England.

A number of circumstances during that time
provided Newton with ideal conditions for concentrated, uninterrupted thought.


Isaac Newton 1642-1727

ewton's book


In 1667, the plague reached Cambridge.
The young mathematics professor fled to
his father's farm in Lincolnshire.

In the peace and quiet of the countryside,
Isaac had all the time in the world to think
about the mechanisms that drive
the solar system.

Puzzling away at the problem of rotating
heavenly bodies, he might even have
found inspiration in the earthy practices
of the country people.

Apple falling
  It is said that the penny finally dropped
when he was working on a sunny day under
an apple tree in his father's orchard.
An apple fell from the tree onto the table
before him. Isaac considered how this might have happened. Why did the apple not fall upwards, or sideways? Why exactly so?
True or not, this story expresses the
essence of the gravitational problem ...
in a world where upwards, downwards
and sideways have no real meaning.