This book is intended as a historical and critical study on the origin of the equations of
motion as established in Newton's Principia. The central question that it aims to answer is
whether it is indeed correct to ascribe to Galileo the inertia principle and the law of falling
bodies. In order to accomplish this task the study begins by considering theories on the
motion of bodies from classical antiquity and especially those of Aristotle. The theories
developed during the Middle Ages and the Renaissance are then reviewed with careful analysis
of the contributions of for example the Merton and Parisian Schools and Galileo's immediate
predecessors Tartaglia and Benedetti. Finally Galileo's work is examined in detail starting
from the early writings. Excerpts from individual works are presented to allow the texts to
speak for themselves and then commented upon. The book provides historical evidence both for
Galileo's dependence on his forerunners and for the major breakthroughs that he achieved. It
will satisfy the curiosity of all who wish to know when and why certain laws have been credited
to Galileo.
