The Sleepwalkers (278 page)
Authors: Arthur Koestler
De
revolutionibus,
Lib.
III,
Cap.
1-4.
Misled
by
these
data,
Copernicus
erroneously
concluded
that
the
rate
of
precession
of
the
equinoxes
was
non-uniform,
and
sought
to
account
for
its
imaginary
fluctuations
and
the
equally
imaginary
fluctuations
of
the
obliquity
of
the
ecliptic,
by
two
independent
oscillatory
motions
of
the
earth's
axis.
De
revolutionibus, Lib. III, Cap. 4.
Commentariolus,
transl. Rosen, p. 57.
He
gives
the
same
reason
in
the
dedicatory
preface
to
the
Revolutions
.
Ptolemy's
system,
he
explains
there,
agrees
fairly
well
with
the
phenomena,
but
it
violates
"the
first
principle
of
uniformity
of
motion".
Rheticus
too,
in
the
Narratio
prima
,
keeps
harping
on
the
same
subject:
"You
see
that
here
in
the
case
of
the
moon
we
are
liberated
from
an
equant
by
the
assumption
of
this
theory...
My
teacher
dispenses
with
equants
for
the
other
planets
as
well..."
(transl.
Rosen,
p.
135).
"...
My
teacher
saw
that
only
on
this
[i.e.
Copernicus']
theory
could
all
the
circles
in
the
universe
be
satisfactorily
made
to
revolve
uniformly
and
regularly
about
their
own
centres,
and
not
about
other
centres
–
an
essential
property
of
circular
motion."
(
Ibid.,
p.
137
).
(Non-uniform
circular
motion
around
a
centre
is]
"a
relation
which
nature
abhors"
(
ibid.,
p.
166
).
De
revolutionibus, Dedication to Pope Paul III.
Ibid.,
Lib. I, Cap. 5.
The
pseudo-
Plutarch
De
placiti
philosophorum,
from
which
Copernicus
quoted
the
passage
about
Philolaus,
Herakleides,
etc.,
says,
a
few
pages
earlier
(II,
24,
quoted
by
Armitage,
p.
88):
"
Aristarchus places the sun among the fixed stars, and holds that the
earth revolves round the sun."
In
Copernicus' version on the manuscript of the Revolutions, this became
transformed into:
" Philolaus perceived the
mobility of the earth, and
some say that Aristarchus of Samos
was of the same opinion."
(
Prowe II
, p. 129.).
But
even
this
watered-down
tribute
is
crossed
out
in
the
manuscript.
The
name
of
Aristarchus
actually
occurs
three
times
in
the
Revolutions
(in
Book
III,
chapters
2,
6
and
13),
but
these
passages
merely
refer
to
his
observations
on
the
obliquity
of
the
ecliptic
and
the
length
of
the
tropical
year.
The
fact
that
Aristarchus
fathered
the
heliocentric
idea
on
which
Copernicus
built
his
system
is
nowhere
mentioned.
Apart
from
the
brief
reference
in
the
pseudo-Plutarch,
Copernicus
knew
about
Aristarchus'
theory
from
the
classic
passage
in
Archimedes'
Sand-reckoner
(see
above,
Part
One,
ch.
III,
3),
which
Regiomontanus,
too,
had
specially
marked
(cf.
Zinner,
p.
178).
Averroes,
Commentary
on
Aristotle's
Metaphysics
,
quoted
by
Rosen,
op.
cit.,
p.
194
f.
De
docta
ignorantia
(Basle,
1514).
Op.
cit., II, 11, 12, quoted by Armitage, p. 89 f.
Ibid.,
p.
102
seq.
,
quoted
by
Koyré,
From
the
Closed
World
to
the
Infinite
Universe
(
Baltimore,
1957),
p.
14
f.
Ibid.,
p. 105seq.
,
quoted
by
Koyré,
pp.
20,
22.
Loc.
cit.
Zinner,
op. cit., p. 97.
Ibid.,
p. 100.
Ibid.,
p. 97.
Cf.
Prowe,
I
,
2,
p.
480
ff.
Zinner,
op. cit., p. 133.
Ibid.,
p. 152.
Loc.
cit.
Ibid.,
p. 135
.
The
daily
rotation
leaves
the
apparent
movements
of
the
firmament
unaltered;
the
annual
revolution
should
produce
a
small
stellar
parallax.
There
is
no
direct
evidence
that
Copernicus
knew
Calcagnini,
but
they
were
contemporaries
at
the
small
University
of
Ferrara,
and
Professor
Antonius
Leutus,
who
on
31
May,
1503,
handed
Copernicus
the
insignia
of
his
doctor
tide,
was
the
godfather
of
Calcagnini.
Butterfield,
op. cit., p. 29.
The
semi-diameter
of
the
earth
was
known
to
be
approx.
4,000
miles
and
Copernicus
believed
the
earth's
distance
from
the
sun
to
be
approx.
1,200
semi-diameters
(
De
revolutionibus,
Lib.
IV,
Cap.
21).
Hence
the
diameter
of
the
earth's
orbit
was
believed
to
be
9.6
million
miles.
