The Sleepwalkers (181 page)

A
month
later,
he
sent
another
anagram
to
Julian
de
Medici:
"
Haec
immatura
a
me
jam
frustra
legunturoy
"
–
"These
immature
things
I
am
searching
for
now
in
vain".
Once
again
Kepler
tried
several
solutions,
among
them:
"
Macula
rufa
in
Jove
est
gyratur
mathem,
etc.
";
^*
then
wrote
to
Galileo
in
exasperation:

"I
beseech
you
not
to
withhold
from
us
the
solution
for
long.
You
must
see
that
you
are
dealing
with
honest
Germans
...
consider
what
embarrassment
your
silence
causes
me."
³²

____________________

Galileo
disclosed
his
secret
a
month
later
–
again
not
directly
to
Kepler,
but
to
Julian
de
Medici:
"
Cynthiae
figuras
aemulatur
mater
amorum
"
–
"The
mother
of
love
[Venus]
emulates
the
shapes
of
Cynthia
[the
moon]."
Galileo
had
discovered
that
Venus,
like
the
moon,
showed
phases
–
from
sickle
to
full
disc
and
back
–
a
proof
that
she
revolved
around
the
sun.
He
also
considered
this
as
proof
of
the
Copernican
system
–
which
it
was
not,
for
it
equally
fitted
the
Egyptian
or
the
Tychonic
system.

In
the
meantime,
Kepler's
dearest
wish:
to
see
for
himself
the
new
marvels,
was
at
last
fulfilled.
One
of
Kepler's
patrons,
the
Elector
Ernest
of
Cologne,
Duke
of
Bavaria,
was
among
the
select
few
whom
Galileo
had
honoured
with
the
gift
of
a
telescope.
In
the
summer
of
1610,
Ernest
was
in
Prague
on
affairs
of
state,
and
for
a
short
period
lent
his
telescope
to
the
Imperial
Mathematicus.
Thus
from
3
August
to
9
September,
Kepler
was
able
to
watch
the
Jupiter
moons
with
his
own
eyes.
The
result
was
another
short
pamphlet,
Observation-Report
on
Jupiter's
Four
Wandering
Satellites
,
³³
in
which
Kepler
confirmed,
this
time
from
first-hand
experience,
Galileo's
discoveries.
The
treatise
was
immediately
reprinted
in
Florence,
and
was
the
first
public
testimony
by
independent,
direct
observation,
of
the
existence
of
the
Jupiter
moons.
It
was
also
the
first
appearance
in
history
of
the
term
"satellite"
which
Kepler
had
coined
in
a
previous
letter
to
Galileo.
³⁴

At
this
point
the
personal
contact
between
Galileo
and
Kepler
ends.
For
a
second
time
Galileo
broke
off
their
correspondence.
In
the
subsequent
months,
Kepler
wrote
several
more
letters,
which
Galileo
left
unanswered,
or
answered
indirectly
by
messages
via
the
Tuscan
Ambassador.
Galileo
wrote
to
Kepler
only
once
during
this
whole
period
of
the
"meeting
of
their
orbits":
the
letter
of
19
August,
1610,
which
I
have
quoted.
In
his
works
he
rarely
mentions
Kepler's
name,
and
mostly
with
intent
to
refute
him.
Kepler's
three
Laws,
his
discoveries
in
optics,
and
the
Keplerian
telescope,
are
ignored
by
Galileo,
who
firmly
defended
to
the
end
of
his
life
circles
and
epicycles
as
the
only
conceivable
form
of
heavenly
motion.

IX CHAOS
AND
HARMONY

1.
Dioptrice

WE
must,
for
the
time
being,
let
Galileo
recede
into
the
background,
and
complete
the
story
of
Kepler's
life
and
work.

Galileo
had
transformed
the
Dutch
spy-glass
from
a
toy
into
an
instrument
of
science,
but
he
had
nothing
to
say
in
explanation
of
why
and
how
it
worked.
It
was
Kepler
who
did
this.
In
August
and
September,
1610,
while
he
enjoyed
the
use
of
the
telescope
borrowed
from
Duke
Ernest
of
Cologne,
he
wrote
within
a
few
weeks
a
theoretical
treatise
in
which
he
founded
a
new
science
and
coined
a
name
for
it:
dioptrics
–
the
science
of
refraction
by
lenses.
His
Dioptrice
¹
is
a
classic
of
a
strikingly
un-Keplerian
kind,
consisting
of
a
hundred
and
forty-one
austere
"definitions",
"axioms",
"problems"
and
"propositions"
without
any
arabesque,
ornament
or
mystic
flights
of
thought.
²
Though
he
did
not
find
the
precise
formulation
of
the
law
of
refraction,
he
was
able
to
develop
his
system
of
geometrical
and
instrumental
optics,
and
to
deduce
from
it
the
principles
of
the
so-called
Astronomical,
or
Keplerian
Telescope.