The Sleepwalkers (267 page)

2

"Nevertheless
the
theories
of
Eudoxus
and
his
followers
fail
to
save
the
phenomena,
and
not
only
those
which
were
first
noticed
at
a
later
date,
but
even
those
which
were
known
before,
and
actually
accepted
by
the
authors
themselves...
I
refer
to
the
fact
that
the
planets
appear
at
times
to
be
near
to
us
and
at
times
to
have
receded.
This
is
indeed
obvious
to
our
eyes
in
the
case
of
some
of
them;
for
the
star
called
after
Aphrodite
and
also
the
star
of
Ares
seem,
in
the
middle
of
their
retrogradations,
to
be
many
times
as
large,
so
much
so
that
the
star
of
Aphrodite
actually
makes
bodies
cast
shadows
on
moonless
nights.
The
moon
also,
even
in
the
perception
of
our
eye,
is
clearly
not
always
at
the
same
distance
from
us,
because
it
does
not
always
seem
to
be
of
the
same
size
under
the
same
conditions
as
to
medium.
The
same
fact
is,
moreover,
confirmed
if
we
observe
the
moon
by
means
of
an
instrument;
for
it
is
at
one
time
a
disk
of
eleven
fingerbreadths,
and
again
at
another
time
a
disk
of
twelve
fingerbreadths,
which
when
placed
at
the
same
distance
from
the
observer
hides
the
moon
(exactly)
so
that
his
eye
does
not
see
it."
Simplicius
on
De
Caelo,
quoted
by
Heath,
op
cit.,
p.
68
f.

3

It
is
perhaps
significant
that
Ptolemy,
alone
among
famous
astronomers,
was
also
a
famous
map-maker.
The
re-discovery
of
his
Geography,
which
was
translated
into
Latin
in
1410,
marked
the
beginning
of
scientific
geography
in
Europe.
Copernicus
and
Kepler,
who
were
also
entrusted
with
map-making,
considered
it
a
tedious
task
to
be
evaded.
Even
Hipparchus
and
Tycho,
the
greatest
star-mapmakers,
avoided
earthly
geography.
But
it
was
Hipparchus
who
outlined
the
principles
of
mathematical
map-making
by
regular
projection,
which
Ptolemy
adopted.
Both
the
epicyclic
universe
and
the
Geography
of
Ptolemy
are
painstaking
executions
of
Hipparchus'
original
designs.

4

From
Al-majisty
,
an
Arabic
corruption
of
the
Greek
Megisty
Syntaxis
.

5

Dreyer,
op. cit., p. 175.

6

Ibid.,
p.
184
.
The
distance
of
the
sun
could
not
be
calculated,
even
approximately,
before
the
invention
of
the
telescope:
Ptolemy
gave
610
earth
diameters
(true
value
11,500);
but
Copernicus
again
knew
no
better:
his
estimate
was
571
earth
diameters
(
Dreyer,
pp.
185
and
339).
As
for
the
fixed
stars,
Ptolemy
knew
that
their
distance
was
enormous
compared
to
the
solar
system;
he
says
that
compared
to
the
sphere
of
the
stars
"the
earth
is
like
a
point".

7

Except,
of course, the ellipticity of the orbits; but see below, note 15.

8

Quoted
by
Ernst
Zinner,
Entstehung
und
Ausbreitung
der
Copernicanischen
Lehre
(
Erlangen,
1943),
p.
49.

9

Loc.
cit.

10

Op.
cit., p. 52 f.

11

Ibid.,
p. 50.

12

Loc.
cit.

13

De
facie orbe lunae, ch. 6, quoted by Heath, op. cit., p. 169.

14

The
Ionian
philosophers
had
been
suspected
of
atheism
and
brought
astronomy
into
somewhat
ill
repute;
but
that
had
been
centuries
before,
and
even
then
they
had
not
come
to
harm.
Plutarch
reports
in
the
Life
of
Nicias,
the
sixthcentury
Greek
general,
that
he
was
afraid
of
eclipses,
that
the
people
were
equally
superstitious,
and
that
"in
those
days
there
was
no
tolerance
for
the
natural
philosophers
or
'babblers
about
things
in
heaven'
as
they
were
called.
They
were
charged
with
explaining
away
the
divine
and
substituting
for
it
irrational
causes,
blind
forces,
and
the
sway
of
necessity.
So
Protagoras
was
banished,
Anaxagoras
was
gaoled
and
it
was
all
that
Pericles
could
do
to
get
him
out;
and
Socrates,
though
he
had
nothing
to
do
at
all
in
the
matter,
was
put
to
death
for
being
a
philosopher.
It
was
only
much
later,
through
the
brilliant
repute
of
Plato,
that
the
reproach
was
removed
from
astronomical
studies
and
access
to
them
opened
up
for
all.
This
was
on
account
of
the
respect
in
which
his
life
was
held
and
because
he
made
natural
laws
subordinate
to
the
authority
of
divine
principles."
(Quoted
by
Farrington,
op.
cit.,
p.
98
f.).