Within the research that I am developing on the transition from a merely kinematic approach to a dynamical one in the history of astronomy and physics, Kepler plays a notable role. He is mainly known for his three planetary laws. However, Kepler did not only try to determine the kinematics of the solar system, he also developed a theory on the causes of the planetary motions. Kepler's theory of forces is not satisfactory, but his idea to provide a dynamical treatment of astronomy is revolutionary. Thus, I will first briefly analyse Kepler's kinematics, later on his basic dynamical ideas. Finally, I will concisely comment on his conceptions.
