Introduction

The most charactristic feature of Einstein's theory is the double role of the fundamental graviational tensor as metric and gravitational potential and the resulting lack of a distinction between kinematics and the dynamics. This property, combined with the nonlinearity of the field equation, is the principal source of the explanatory power on well as the conceptional and computational intricacies of Einstein's theory. This is demonstrated by considering bodies and their laws of motion, isolated systems and approximation methods for the equations of motion. (Auth.)