  This article--summarizing the authors' then novel formulation of General
Relativity--appeared as Chapter 7 of an often cited compendium edited by L.
Witten in 1962, which is now long out of print. Intentionally unretouched, this
posting is intended to provide contemporary accessibility to the flavor of the
original ideas. Some typographical corrections have been made: footnote and
page numbering have changed--but not section nor equation numbering etc. The
authors' current institutional affiliations are encoded in:
<EMAIL_ADDRESS><EMAIL_ADDRESS><EMAIL_ADDRESS>.
