During the Modern period, planetary motion was described by Newton through force. Leibniz thought Newton was turning planetary motion to an "occult quality", as something not fully intelligible. Leibniz viewed the proper explanation as being completely mechanical, that only by an "impressed impetus" can an object move. As his antithesis, Leibniz proposed the vortex theory as being responsible for planetary motion. This is a very brief preface, but do you believe that Newton's explanation of planetary force is intelligible? I am beginning my studies in physics and find its progression fascinating. I am interested to read responses from those who have been in physics much longer than I.