published in 1687
3 Law of motion
A body continues at rest or in uniform motion in a straight line unless
acted upon by some force.
A bodys change of motion is proportional to the force acting on it
and is in the direction of the force.
When one body exerts a force on a second body, the second body
exerts an equal and opposite force back on the first body.
There is an attractive force between all bodies, proportional to their
mass, and inversely proportional to the square of their distance.