The Sleepwalkers (17 page)

The
motives
which
led
to
this
tremendous
innovation
we
can
only
guess.
Perhaps
it
was
the
realization
that
there
is
something
illogical
in
the
apparent
movements
of
the
planets.
It
seemed
crazy
that
the
sun
and
planets
should
turn
round
the
earth
once
a
day,
but
at
the
same
time
slowly
crawl
along
the
Zodiac
on
their
annual
revolutions.
Everything
would
be
much
simpler
if
one
assumed
that
the
daily
revolution
of
the
entire
sky
was
an
illusion
caused
by
the
earth's
own
motion.
If
the
earth
existed
free
and
unattached
in
space,
could
she
not
also
move
?
Yet
the
apparently
obvious
idea
of
letting
the
earth
rotate
on
her
own
axis
did
not
occur
to
Philolaus.
Instead,
he
made
her
revolve,
in
twenty-four
hours,
round
an
extraneous
point
in
space.
By
describing
one
complete
circle
a
day,
the
observer
on
earth
would
have
the
illusion,
like
a
traveller
on
a
roundabout,
that
the
whole
cosmic
fair
was
turning
in
the
opposite
direction.

In
the
centre
of
his
roundabout,
Philolaus
placed
the
"watchtower
of
Zeus",
also
called
"the
hearth
of
the
universe"
or
the
"central
fire".
But
this
"central
fire"
is
not
to
be
confused
with
the
sun.
It
could
never
be
seen;
for
the
inhabited
part
of
the
earth
–
Greece
and
its
neighbours
–
was
always
turned
away
from
it,
as
the
dark
side
of
the
moon
is
always
turned
away
from
the
earth.
Moreover,
between
the
earth
and
the
central
fire
Philolaus
inserted
an
invisible
planet:
the
antichton
or
counter-earth.
Its
function
was,
apparently,
to
protect
the
antipodes
from
being
scorched
by
the
central
fire.
The
ancient
belief
that
the
farwestern
regions
of
the
earth,
beyond
the
straits
of
Gibraltar,
are
shrouded
in
eternal
twilight
²
was
now
explained
by
the
shadow
which
the
counter-earth
threw
on
those
parts.
But
it
is
also
possible
–
as
Aristotle
contemptuously
remarks
–
that
the
counterearth
was
invented
merely
to
bring
the
number
of
moving
things
in
the
universe
up
to
ten,
the
sacred
number
of
the
Pythagoreans.
³

Around
the
central
fire,
then,
revolved
in
concentric
orbits
these
nine
bodies:
the
antichton
innermost,
then
the
earth,
the
moon,
the
sun
and
the
five
planets;
then
came
the
sphere
carrying
all
the
fixed
stars.
Beyond
this
outer
shell
there
was
a
wall
of
fiery
ether,
enclosing
the
world
from
all
sides.
This
"outer
fire"
was
the
second
and
main
source
from
which
the
universe
drew
its
light
and
breath.
The
sun
served
merely
as
a
kind
of
transparent
window
or
lens,
through
which
the
outer
light
was
filtered
and
distributed.
The
picture
reminds
one
of
Anaximander's
holes
in
the
flame-filled
tyre.
But
these
fantastic
imaginations
were
perhaps
less
fantastic
than
the
notion
of
a
ball
of
fire
hurtling
across
the
sky
through
eternity,
without
burning
out;
a
preposterous
idea
at
which
the
mind
boggles.
Looking
at
the
sky
with
eyes
washed
clean
of
theories,
is
it
not
more
convincing
to
regard
the
sun
and
stars
as
holes
in
the
curtain
enclosing
the
world?

The
only
heavenly
object
considered
to
be
similar
to
the
earth
was
the
moon.
It
was
supposed
to
be
inhabited
by
plants
and
animals
fifteen
times
as
strong
as
ours,
because
the
moon
enjoyed
daylight
for
fifteen
days
in
succession.
Other
Pythagoreans
thought
that
the
lights
and
shadows
on
the
moon
were
reflections
of
our
oceans.
As
for
eclipses,
some
were
caused
by
the
earth,
some
by
the
counter-earth,
which
also
accounted
for
the
faint
ashen
light
on
the
lunar
disc
at
new
moon.
Still
others
seem
to
have
assumed
the
existence
of
several
counter-earths.
It
must
have
been
a
lively
debate.

2.
Herakleides and the Sun-Centred Universe

In
spite
of
its
poetic
oddities,
the
system
of
Philolaus
opened
up
a
new
cosmic
perspective.
It
broke
away
from
the
geocentric
tradition
–
the
sturdy
conviction
that
this
earth
occupies
the
centre
of
the
Universe,
from
which,
massive
and
immobile,
it
never
budges
an
inch.