I have never accepted Einstein's thought pattern on this and other matters. I have examined his equation to calculate the advamce of Mercury's perihelion and have also calculated the advance in the case of a circular orbit, using the same equation. What I found is that if you remove the correction term for elliptical orbits ( r(1 - e2) from Einstein's equation, the result is not nil advance, but rather it remains the same but is expressed as a length along the circumference of orbit and not an angular measure. What Einstein said was that the greater velocity during the closer approach at perhelion adds a little extra mass to the system which makes the orbit advance. If the orbital velocity is constant as is for the circular case, then Einstein's equation ought to reflect his reasoning and show no advance at all. So what makes the orbit advance if it is circular? Is Einstein's reasoning right or wrong on this point?