FIELD THEORIES OF GRAVITATION: THE FIRST FIFTY YEARS 237
also open a way for a derivation of the Einstein-Grossmann gravitation equations
in a way independent of physical assumptions. The proof of the existence or non-
existence of such a connection would be an important theoretical advance.' A final
footnote states that one of the reasons given by Einstein and Grossmann [El] for
the nonexistence of such a connection was incorrect, namely, the allegedly wrong
weak-field properties of the Ricci tensor (Chapter 12).
Thus, early in 1914, just fifty years after Maxwell's first attempt at a gravita-
tion field theory, Einstein was not yet quite there but he was closing in, as the
final remark of the Einstein-Fokker paper clearly indicates. That it took him
almost another two years before he had the final answer was due in part to
important changes which were about to take place in his personal life, as we shall
see next.
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