Authors: Arthur Koestler
The Sleepwalkers (273 page)
Johannes
Kepler,
Gesammelte
Werke
,
Vol.
III,
Munich,
1937.
"Kepler
to
Longomontanus,
spring
1605",
Gesammelte
Werke
,
Vol.
XV,
Munich,
1951,
p.
134
seq.
Rheticus,
op.
cit.
,
p.
163
f.
Ibid.,p.
188
See
below, note 13 to ch. 2.
Canon
Alexander
Sculteti,
about
whom
more
below.
Not
to
be
confused
with
Bernard
Sculteti,
see
above
pp.
131,
146.
De
Lateribus et Angulis Triangulorum, Wittenberg, 1542.
Zinner,
op. cit., p. 243.
59
The
full text of Osiander's preface is as follows (transl. Rosen, op.
cit., p. 24 f.):
"TO
THE READER CONCERNING THE HYPOTHESES OF THIS WORK
Since
the
novelty
of
the
hypotheses
of
this
work
has
already
been
widely
reported,
I
have
no
doubt
that
some
learned
men
have
taken
serious
offence
because
the
book
declares
that
the
earth
moves,
and
that
the
sun
is
at
rest
in
the
centre
of
the
universe;
these
men
undoubtedly
believe
that
the
liberal
arts,
established
long
ago
upon
a
correct
basis,
should
not
be
thrown
into
confusion.
But
if
they
are
willing
to
examine
the
matter
closely,
they
will
find
that
the
author
of
this
work
has
done
nothing
blameworthy.
For
it
is
the
duty
of
an
astronomer
to
compose
the
history
of
the
celestial
motions
through
careful
and
skillful
observation.
Then
turning
to
the
causes
of
these
motions
or
hypotheses
about
them,
he
must
conceive
and
devise,
since
he
cannot
in
any
way
attain
to
the
true
causes,
such
hypotheses
as,
being
assumed,
enable
the
motions
to
be
calculated
correctly
from
the
principles
of
geometry,
for
the
future
as
well
as
for
the
past.
The
present
author
has
performed
both
these
duties
excellently.
For
these
hypotheses
need
not
be
true
nor
even
probable;
if
they
provide
a
calculus
consistent
with
the
observations,
that
alone
is
sufficient.
Perhaps
there
is
someone
who
is
so
ignorant
of
geometry
and
optics
that
he
regards
the
epicycle
of
Venus
as
probable,
or
thinks
that
it
is
the
reason
why
Venus
sometimes
precedes
and
sometimes
follows
the
sun
by
forty
degrees
and
even
more.
Is
there
anyone
who
is
not
aware
that
from
this
assumption
it
necessarily
follows
that
the
diameter
of
the
planet
in
perigee
should
appear
more
than
four
times,
and
the
body
of
the
planet
more
than
sixteen
times,
as
great
as
in
the
apogee,
a
result
contradicted
by
the
experience
of
every
age?
In
this
study
there
are
other
no
less
important
absurdities,
which
there
is
no
need
to
set
forth
at
the
moment.
For
it
is
quite
clear
that
the
causes
of
the
apparent
unequal
motions
are
completely
and
simply
unknown
to
this
art.
And
if
any
causes
are
devised
by
the
imagination,
as
indeed
very
many
are,
they
are
not
put
forward
to
convince
anyone
that
they
are
true,
but
merely
to
provide
a
correct
basis
for
calculation.
Now
when
from
time
to
time
there
are
offered
for
one
and
the
same
motion
different
hypotheses
(as
eccentricity
and
an
epicycle
for
the
sun's
motion),
the
astronomer
will
accept
above
all
others
the
one
which
is
the
easiest
to
grasp.
The
philosopher
will
perhaps
rather
seek
the
semblance
of
the
truth.
But
neither
of
them
will
understand
or
state
anything
certain,
unless
it
has
been
divinely
revealed
to
him.
Let
us
therefore
permit
these
new
hypotheses
to
become
known
together
with
the
ancient
hypotheses,
which
are
no
more
probable;
let
us
do
so
especially
because
the
new
hypotheses
are
admirable
and
also
simple,
and
bring
with
them
a
huge
treasure
of
very
skilful
observations.
So
far
as
hypotheses
are
concerned,
let
no
one
expect
anything
certain
from
astronomy,
which
cannot
furnish
it,
lest
he
accept
as
the
truth
ideas
conceived
for
another
purpose,
and
depart
from
this
study
a
greater
fool
than
when
he
entered
it.
Farewell."
Copernicus'
letter, dated 1 July, 1540, is lost.
Osiander's
answer
was
dated
20
April,
1541.
It
is
quoted
in
Kepler
Apologia
Tychonis
contra
Ursum
,
published
in
Kepler
Opera
Omnia
,
ed.
Frisch,
I,
pp.
236-276.
