  The mantra about gravitation as curvature is a misnomer. The curvature tensor
for a standard of rest does not describe acceleration in a gravitational field
but the \underline{gradient} of the acceleration (e.g. geodesic deviation). The
gravitational field itself (Einstein 1907) is essentially an accelerated
reference system. It is characterized by a field of orthonormal four-legs in a
Riemann space with Lorentz metric. By viewing vectors at different events
having identical leg-components as parallel (teleparallelism) the geometry in a
gravitational field defines torsion. This formulation of Einstein's 1907
principle of equivalence uses the same Riemannian metric and the same 1916
field equations for his theory of gravitation and fulfills his vision of
General Relativity.
