  We review and strengthen the arguments given by Einstein to derive his first
gravitational field equation for static fields and show that, although it was
ultimately rejected, it follows from General Relativity (GR) for negligible
pressure. Using this equation and considerations folowing directly from the
equivalence principle (EP), we show how Schwarzschild metric and other vacum
metrics can be obtained immediately. With this results and some basic
principles, we obtain the metric in the general spherically symmetric case and
the corresponding hydrostatic equilibrium equation. For this metrics we obtain
the motion equations in a simple and exact manner that clearly shows the three
sources of difference (implied by various aspects of the EP) with respect to
the Newtonian case and use them to study the classical tests of GR. We comment
on the origin of the problems of Einstein first theory of gravity and discuss
how, by removing it the theory could be made consistent and extended to include
rotations, we also comments on various conceptual issues of GR as the origin of
the gravitational effect of pressure.
