  Action at distance in Newtonian physics is replaced by finite propagation
speeds in classical post--Newtonian physics. As a result, the differential
equations of motion in Newtonian physics are replaced by functional
differential equations, where the delay associated with the finite propagation
speed is taken into account. Newtonian equations of motion, with
post--Newtonian corrections, are often used to approximate the functional
differential equations. In ``On the origin of quantum mechanics'', preprint,
physics/0505181, May 2005, a simple atomic model based on a functional
differential equation which reproduces the quantized Bohr atomic model was
presented. The unique assumption was that the electrodynamic interaction has a
finite propagation speed. In ``On the origin of the gravitational quantization:
The Titius--Bode Law'', preprint, physics/0507072, Jul 2005, a simple
gravitational model based on a functional differential equation which gives a
gravitational quantification and an explanation of the modified Titius--Bode
law is described. Firstly, in this work, we recall the calculations made by
Einstein to arrive at the explanation of the anomalous precession of Mercury's
perihelion. Secondly, we recover an ancient work of Gerber in 1898 as a
precursor of the retarded theories. In this paper Gerber gave an explanation of
the anomalous precession of the Mercury's perihelion in terms of a
velocity--dependent potential. In this paper an explanation of the anomalous
precession of Mercury's perihelion is given in terms of a simple retarded
potential, which, at first order, coincides with Gerber's potential, and which
agrees with the author's previous works.
