The Sleepwalkers (33 page)

Their
main
concern
was
"to
save
the
appearances".
The
original
meaning
of
this
ominous
phrase
was
that
a
theory
must
do
justice
to
the
observed
phenomena,
or
"appearances";
in
plain
words,
that
it
must
agree
with
the
facts.
But
gradually,
the
phrase
came
to
mean
something
different.
The
astronomer
"saved"
the
phenomena
if
he
succeeded
in
inventing
a
hypothesis
which
resolved
the
irregular
motions
of
the
planets
along
irregularly
shaped
orbits
into
regular
motions
along
circular
orbits
–
regardless
whether
the
hypothesis
was
true
or
not
,
i.e.
whether
it
was
physically
possible
or
not.
Astronomy,
after
Aristotle,
becomes
an
abstract
sky-geometry,
divorced
from
physical
reality.
Its
principal
task
is
to
explain
away
the
scandal
of
noncircular
motions
in
the
sky.
It
serves
a
practical
purpose
as
a
method
for
computing
tables
of
the
motions
of
the
sun,
moon
and
planets;
but
as
to
the
real
nature
of
the
universe,
it
has
nothing
to
say.

Ptolemy
himself
is
quite
explicit
about
this:
"We
believe
that
the
object
which
the
astronomer
must
strive
to
achieve
is
this:
to
demonstrate
that
all
the
phenomena
in
the
sky
are
produced
by
uniform
and
circular
motions..."
¹⁶
And
elsewhere:
"Having
set
ourselves
the
task
to
prove
that
the
apparent
irregularities
of
the
five
planets,
the
sun
and
moon
can
all
be
represented
by
means
of
uniform
circular
motions,
because
only
such
motions
are
appropriate
to
their
divine
nature...
We
are
entitled
to
regard
the
accomplishment
of
this
task
as
the
ultimate
aim
of
mathematical
science
based
on
philosophy."
¹⁷
Ptolemy
also
makes
it
clear
why
astronomy
must
renounce
all
attempts
to
explain
the
physical
reality
behind
it:
because
the
heavenly
bodies,
being
of
a
divine
nature,
obey
laws
different
from
those
to
be
found
on
earth.
No
common
link
exists
between
the
two;
therefore
we
can
know
nothing
about
the
physics
of
the
skies.

Ptolemy
was
a
wholehearted
Platonist;
the
effect
of
the
twin-stars
on
the
course
of
science
now
makes
itself
fully
felt.
The
divorce
which
they
effected
between
the
four
elements
of
the
sublunary
region
and
the
fifth
element
of
the
heavens,
leads
directly
to
a
divorce
of
sky-geometry
from
physics,
of
astronomy
from
reality.
The
split
world
is
reflected
in
the
split
mind.
It
knows
that
in
reality
the
sun
has
a
physical
influence
on
the
planets;
but
reality
is
no
longer
its
concern.
¹⁸

The
situation
is
summed
up
in
a
striking
passage
by
Theon
of
Smyrna,
a
contemporary
of
Ptolemy.
After
expressing
his
opinion
that
Mercury
and
Venus
may,
after
all,
be
revolving
round
the
sun,
he
goes
on
to
say
that
the
sun
should
be
called
the
heart
of
the
universe,
which
is
both
"a
world
and
an
animal".
"But,"
he
reflects,
"in
animated
bodies
the
centre
of
the
animal
is
different
from
the
centre
of
its
mass.
For
instance,
for
us
who
are
both
men
and
animals,
the
centre
of
the
animated
creature
is
in
the
heart,
always
in
motion
and
always
warm,
and
therefore
the
source
of
all
the
faculties
of
the
soul,
of
desire,
imagination
and
intelligence;
but
the
centre
of
our
volume
is
elsewhere,
about
the
navel...
Similarly
...
the
mathematical
centre
of
the
universe
is
where
the
earth
is,
cold
and
immovable,
but
the
centre
of
the
world
as
an
animal
is
in
the
sun,
which
is,
so
to
say,
the
heart
of
the
universe."
¹⁹

The
passage
is
both
appealing
and
appalling;
it
strikes
a
note
which
will
reverberate
throughout
the
Dark
and
Middle
Ages.
It
appeals
to
the
archetypal
craving
to
comprehend
the
world
as
a
live,
pulsating
animal;
and
it
appalls
by
its
unholy
mix-up
of
allegorical
and
physical
statements,
by
its
pedantic
variations
on
the
inspired
Platonic
leg-pull.
The
contrast
between
navel
and
heart
is
witty
but
unconvincing;
it
does
not
explain
why
two
planets
should
revolve
round
the
heart
and
the
other
three
round
the
navel.
Did
Theon
and
his
readers
believe
in
this
sort
of
thing?
The
answer
is,
apparently,
that
one
compartment
of
their
minds
did,
the
other
did
not;
the
process
of
divorcement
was
nearly
completed.
Observational
astronomy
was
still
progressing;
but
what
a
regression
in
philosophy
compared
to
the
Pythagorean,
and
even
the
Ionian,
school
of
seven
centuries
before!