The unravelling of Einstein's erratic quest for the correct field equations can be traced in a dramatic series of weekly communications from Einstein to the Prussian Academy of Science.
On the four Thursdays of November 1915, he presented to the Prussian Academy of Science a paper of fundamental importance
1915, November 11: Einsein submits "On the General Theory of Relativity (Addendum)", in which he introduces the hypothesis that macroscopic matter could eventually be reduced to "purely electromagnetic processes".
1915, November 18: Einstein submits "Explanation of the Perihelion Motion of Mercury from the General Theory of Relativity", in which a calculation based on the new theory provides the expected result (45'' instead of 18'')
1915, November 25: Einstein submits the definitive version of general relativity in paper titled "The Field Equations of Gravitation", in which he proposed three alternative systems of gravitational field equations, the last two of which were generally covariant.
 The "Entwurf" theory was Einstein's theory of general relativity between spring 1913 and October 1915, elaborated in collaboration with Marcel Grossmann. On beginning of November 1915, Einstein could say "I lost trust in the field equations i have derived, and instead, looked for a way to limit the possibilities in a natural way. In this pursuit I arrived at the demand of general covariance, a demand from which I parted, though with a heavy heart, three years ago when i worked together with my friend Grossmann."
 "One now has to remember that by our knowledge "matter" is not to be perceived as something primitively given or physically plain. There even have those, and not just a few, who hope to reduce matter to purely electrodynamic processes, which of course would have to be done in a theory more completed than MAXWELL's electrodynamics".