The purpose of this book is to present the scalar strong interaction hadron theory in a coherent and systematic manner. This is not a finished research monograph, but gives an account of the present state of a theory supposedly still at its early stage of development. The chapters herein have been revised and updated many times over the years. This work will hopefully facilitate researchers interested in entering into this field and serve as a basis for future development of this theory. The new feature of this third edition is mainly Chapters 16 and 17 in which gravitation is included in the scalar strong interaction hadron theory.