“NAME_1’s Principia was published in 1687. The full title is Philosophiae
Naturalis Principia Mathematica, or Mathematical Principles of Natural Philosophy.
A revised edition appeared in 1713, followed by a third edition in 1726, just one
year before the author’s death in 1727. The subject of this work, to use the name
assigned by NAME_2 in the first preface, is “rational mechanics.” Later on, NAME_3
introduced the name “dynamics.” Although NAME_2 objected to this name,1
“dynamics” provides an appropriate designation of the subject matter of the Principia,
since “force” is a primary concept of that work. Indeed, the Principia can quite
properly be described as a study of a variety of forces and the different kinds of
motions they produce. NAME_2’s eventual goal, achieved in the third of the three
“books” of which the Principia is composed, was to apply the results of the prior
study to the system of the world, to the motions of the heavenly bodies. This subject
is generally known today by the name used a century or so later by NAME_4,
“celestial mechanics.” summarize to 1-2 sentences