Einstein is Newton with space curved
  The two defining features of the Einsteinian gravity are that it is self interactive as well as it links universally to all particles including zero mass particles. In the process of obtaining the Schwarzshild solution for gravitational field of a mass point, we would demonstrate how are these features incorporated? We would also show, unlike the Newtonian gravity, why the gravitational potential in the Schwarzshild solution can have its zero only at infinity and nowhere else;i.e. it is determined absolutely. We also consider particle orbits to expose certain insightful and subtle points of concept and principle. 
Naresh Dadhich
gr-qc astro-ph.HE