The Sleepwalkers (78 page)

The
next
question
is,
whether
Copernicus
actually
read
the
preface,
and
what
his
reactions
to
it
were.
We
have
two
contradictory
statements
on
this
point:
one
from
Rheticus,
one
from
Kepler.
Kepler's
text
runs
as
follows:

"It
is
a
most
absurd
fiction,
I
admit,
that
the
phenomena
of
nature
can
be
explained
by
false
causes.
But
this
fiction
is
not
in
Copernicus.
He
thought
that
his
hypotheses
were
true,
no
less
than
did
those
ancient
astronomers
of
whom
you
speak.
And
he
did
not
merely
think
so,
but
he
proves
that
they
are
true.
As
evidence,
I
offer
this
work.

Do
you
wish
to
know
the
author
of
this
fiction,
which
stirs
you
to
such
great
wrath?
Andreas
Osiander
is
named
in
my
copy,
in
the
handwriting
of
Jerome
Schreiber,
of
Nuremberg.
Andreas,
who
supervised
the
printing
of
Copernicus'
work,
regarded
the
Preface,
which
you
declare
to
be
most
absurd,
as
most
prudent
(as
can
be
inferred
from
his
letter
to
Copernicus)
and
placed
it
on
the
title
page
of
the
book
when
Copernicus
was
either
already
dead
or
certainly
unaware
[of
what
Osiander
was
doing]."
⁶⁴

Rheticus'
evidence
is
contained
in
a
letter
by
the
Professor
of
Mathematics,
Johannes
Praetorius,
to
a
correspondent.
Praetorius
was
an
intimate
friend
of
Rheticus
and
a
reliable
scholar.
His
letter
says:

"Concerning
the
Preface
in
Copernicus'
book,
there
has
been
uncertainty
about
its
author.
However,
it
was
Andreas
Osiander
...
who
did
the
Preface.
For
it
was
under
his
charge
that
Copernicus'
book
was
first
printed
in
Nuremberg.
And
some
of
the
first
pages
were
sent
to
Copernicus,
but
a
short
while
later
Copernicus
died,
before
he
could
see
the
whole
work.
Rheticus
used
to
assert
with
seriousness
that
this
Preface
of
Osiander's
was
clearly
displeasing
to
Copernicus,
and
that
he
was
more
than
a
little
irritated
by
it.
This
seems
likely,
for
his
own
intention
was
different,
and
what
he
would
have
liked
the
Preface
to
say
is
clear
from
the
contents
of
his
Dedication
[to
Paul
III]...
The
title
also
was
changed
from
the
original
beyond
the
author's
intentions,
for
it
should
have
been:
De
revolutionibus
orbium
mundi
,
whereas
Osiander
made
it:
Orbium
coelestium
."
⁶⁵

Praetorius'
letter
was
written
in
1609.
Kepler's
Astronomia
Nova
,
in
which
the
quoted
passage
appears,
was
published
in
the
same
year.
It
was
sixty-six
years
after
the
event.
Which
of
the
two
opposite
versions
should
we
trust?

To
solve
the
puzzle,
we
must
compare
(a)
the
contents,
(b)
the
source,
and
(c)
the
motive
behind
each
of
the
two
statements.
The
content
of
Kepler's
is
vague:
Copernicus
was
"either
already
dead
or
certainly
unaware
of"
Osiander's
preface.
It
is
based
on
hearsay:
Kepler's
source
is
his
old
teacher
Michael
Maestlin,
whose
own
knowledge
of
the
events
was
third-hand.
⁶⁶
Praetorius'
statement
is
precise,
the
incidental
detail
about
the
changed
title
is
convincing,
and
his
information
came
straight
from
the
horse's
mouth,
as
it
were:
from
Rheticus,
whose
guest
he
had
been
on
two
occasions,
in
1569
and
1571.
⁶⁷
As
for
motive,
Kepler's
statement
on
Copernicus'
beliefs
appears
as
a
motto
at
the
beginning
of
Kepler's
Astronomia
Nova
(which
is
based
on
the
Copernican
hypothesis)
and
clearly
serves
a
propagandistic
purpose;
^67a
whereas
Praetorius'
version
is
contained
in
a
chatty
letter,
with
no
apparent
motive
at
all.

The
balance
is
thus
clearly
in
favour
of
Praetorius,
and
the
conclusion
seems
to
be
that,
contrary
to
accepted
opinion,
Copernicus
was
acquainted
with
Osiander's
Preface.
Oddly
enough,
the
Praetorius
document,
as
far
as
I
know,
escaped
the
attention
of
all
biographers,
except
the
most
recent
and
scholarly
among
them,
the
German
astronomer
Ernst
Zinner.
As
I
felt
doubtful
about
my
own
conclusions,
I
wrote
to
Professor
Zinner
and
received
the
following
reply:

"I
do
not
share
your
doubts.
We
can
regard
it
as
certain
that
Copernicus
knew
Osiander's
preface
for
which
he
was
prepared
by
Osiander's
previous
letters
of
1540-41.
Praetorius'
statements
are
trustworthy
for
they
were
based
on
direct
communications
from
Rheticus,
who
knew
best.
Praetorius
...
was
a
conscientious
scholar
and
left
us
important
information
and
works.
At
any
rate,
his
testimony
is
more
important
than
the
vague
testimony
of
Kepler,
who
derived
his
information
from
Maestlin,
who
in
turn
was
too
remote
from
the
whole
affair...
Is
it
not
self-evident
that
Rheticus,
who
had
snatched
the
manuscript
from
Copernicus
almost
by
force,
as
it
were,
did
forward
its
galleys
to
its
author?
I
imagine
that
all
the
galleys
were
sent
to
Copernicus
in
the
course
of
time,
so
that
at
his
death
the
whole
book
was
assembled
in
print,
as
Giese
states..."
⁶⁸