DOC. 42
SPECIAL AND GENERAL RELATIVITY 397
158
Relativity
the
last of the Cartesians. But it
is
not to
be denied
that,
even
at
this
primitive stage, something unsatisfactory clings to
the
concept
of
space,
or
to
space
thought
of
as an
independent
real
thing.
The
ways
in which bodies
can
be
packed
into
space
(e.g.
the
box)
are
the
subject
of three-dimensional Euclidean
geome-
try,
whose axiomatic
structure
readily
deceives
us
into
forget-
ting
that it
refers
to
realisable situations.
If
now
the
concept
of
space
is
formed
in
the
manner
out-
lined
above,
and
following
on
from
experience
about
the
"fill-
ing"
of the
box,
then
this
space
is
primarily
a
bounded
space.
This
limitation does
not appear to
be
essential, however, for
apparently
a
larger
box
can always
be introduced
to
enclose
the smaller
one.
In this
way space appears
as something un-
bounded.
I
shall
not
consider here how
the
concepts
of
the three-
dimensional and the Euclidean
nature
of
space
can
be traced
back
to relatively primitive experiences.
Rather, I
shall
con-
sider first
of
all from
other
points
of view the role
of
the
concept
of
space
in the
development
of
physical
thought.
When
a
smaller box
s
is
situated,
relatively
at
rest,
inside the
hollow
space
of
a
larger
box
S,
then the
hollow
space
of
s
is
a
part
of the hollow
space
of
S,
and
the
same
"space,"
which
contains both
of
them,
belongs
to
each
of
the
boxes. When
s
is
in motion with
respect
to
S,
however,
the
concept
is
less
simple.
One
is
then
inclined
to
think that
s
encloses
always
the
same space,
but
a
variable
part
of the
space
S.
It then
becomes
necessary
to
apportion
to
each box
its
particular