DOC.
13
GENERALIZED THEORY OF RELATIVITY
171
orthogonal
linear substitutions but also with
respect
to
a
much wider
group
of
substitutions. But
already
the
mere
fact that
we were
not
able
to
find the
(most
general) group
of substitutions associated with
our
gravitational equations
makes
it
unjustifiable
for
us
to
press
this
argument.