Foreword.- Introduction.- General Plan of the Essay.- Chapter 1: The Three Levels of Aristotle's Theory of Material Bodies in Forced Motion.- Chapter 2: Heaviness, Lightness, Sinking and Floating.- Chapter 3: Some Refinements of the Basic Theory.- Chapter 4: The Dynamics of Balance: The Winch and the Lever in the Pseudo Aristotelian Mechanical Problems.- Chapter 5: Hipparchus on the theory of Prolonged Motion.- Appendix 1: Do Heavy Objects become Heavier as they Approach their Natural Place?.- Appendix 2: A Threshold of Motion in Time, as well as in Force?.- Appendix 3: A Mathematical Formulation of Aristotle's Theory of Forced Horizontal Motion.- Appendix 4: A Mathematical Formulation of Aristotle's Theory of Natural and Forced Vertical Motion.- Appendix 5: A Mathematical Formulation of Hipparchus's Theory of Vertical Motion.- Appendix 6: Alternative Translations of the Quotations Used in the Main Text.