  Let $r(\varphi)$ denote the orbit of Mercury. We compare the formulae
obtained via general relativity for $r(\varphi)$ and for the corresponding
perihelion precession angle $\Delta \varphi$, with the formulae obtained via
the relativistic gravitational law, $F=GMm\gamma^6/r^2$. The latter law can be
derived from Newton's gravitational law by employing the gravitational rather
than the rest masses of the Sun and Mercury. Remarkably, it is found that the
two expressions for the dominant part of $r(\varphi)$ are identical and that
the two expressions for $\Delta\varphi$ are also identical.
