The Sleepwalkers (244 page)

One
may
again
note
in
passing,
that
this
Janus-faced
quality
is
equally
present,
though
expressed
in
less
poetic
language,
in
the
contemporary
theories
of
matter
as
both
a
corpuscle
and
a
wave,
according
to
which
face
it
presents.
Magnetism,
gravity
and
action-at-a-distance
have
not
lost
an
iota
of
their
baffling
mystery
since
Gilbert.

Kepler
was
not
the
only
victim
of
this
inevitable
confusion;
Galileo
too
believed
that
Gilbert
had
provided
the
explanation
why
the
earth's
axis
always
points
in
the
same
direction
in
space
–
the
axis
was
simply
a
kind
of
magnetic
needle.
Even
Robert
Boyle,
the
father
of
modern
chemistry
and
one
of
the
principal
influences
on
Newton,
thought
that
gravity
may
be
due
to
"magnetic
vapours"
issuing
from
the
earth.

Only
the
most
implacably
sceptical
and
logical
brain
among
them
all,
that
of
Descartes,
repudiated
magnetism,
gravity
and
any
form
of
action-at-a-distance.
Descartes
took
matters
a
decisive
step
forward
by
letting
bodies
persist
in
their
motion,
not
in
a
Galilean
circle,
but
in
a
straight
line.
¹
At
the
same
time,
however,
he
took
an
equally
important
step
backward
by
explaining
magnetism
and
gravity
as
whirlpools
in
the
ether.
It
is
a
measure
of
Newton's
daring
that
even
Descartes,
who
promised
to
reconstruct
the
whole
universe
from
matter
and
extension
alone,
who
invented
the
most
beautiful
tool
of
mathematical
reasoning,
analytical
geometry,
who
was
more
ruthless
in
his
methods
of
thought
than
any
of
his
predecessors
–
that
even
Descartes,
this
Robespierre
of
the
scientific
revolution,
rejected
attraction-at-a-distance
at
the
price
of
filling
all
space
with
monstrous
eddies
and
vortices.
Like
Kepler
who
hit
on
the
concept
of
gravity,
then
kicked
it
away,
like
Galileo
who
rejected
even
the
moon's
influence
on
the
tides,
Descartes'
wide-open
mind
boggled
in
horror
at
the
idea
of
ghost
arms
clutching
through
the
void
–
as
unprejudiced
intelligence
was
indeed
bound
to
do,
until
"universal
gravity"
or
"electro-magnetic
field"
became
verbal
fetishes
which
hypnotised
it
into
quiescence,
disguising
the
fact
that
they
are
metaphysical
concepts
dressed
in
the
mathematical
language
of
physics.

4.
Enter Gravity

These,
then,
were
the
pieces
of
the
chaotically
scattered
jigsaw
puzzle
confronting
Newton.
Contradictory
theories
regarding
the
behaviour
of
objects
in
space
in
the
absence
of
interfering
forces;
contradictory
theories
about
the
forces
which
make
planets
revolve;
confusing
fragments
of
information
about
inertia
and
momentum,
weight
and
free
fall,
gravity
and
magnetism;
doubts
about
the
location
of
the
centre
of
the
universe
and
whether
it
had
a
centre;
and
overshadowing
it
all,
the
question
where
the
God
of
the
Scriptures
fitted
into
the
picture.

There
had
been
some
vague
conjectures
in
the
right
direction,
but
unsupported
by
precise
argument.
The
French
mathematician,
Giles
Peron
de
Roberval,
for
instance,
had
suggested
in
the
year
following
Galileo's
death
that
all
matter
in
the
universe
was
drawn
together,
and
that
the
moon
would
fall
on
the
earth
if
the
ether
did
not
act
as
a
supporting
cushion
between
them.
Giovanni
Borelli,
who
occupied
Galileo's
erstwhile
chair
in
Pisa,
took
up
an
ancient
Greek
suggestion
that
the
moon
behaved
"like
a
stone
in
a
sling"
whose
flying
force
prevented
it
from
falling
to
the
earth.
But
he
contradicted
himself
by
believing,
with
Kepler,
that
the
moon
needed
to
be
pushed
round
in
a
circle
by
an
invisible
broom
–
that
is,
that
the
moon
had
no
impetus
of
its
own;
then
why
should
it
try
to
fly
away?

Newton
was
twenty-four
when,
in
1666,
he
found
the
key
to
the
solution;
but
then
his
interest
turned
to
other
matters,
and
it
was
only
twenty
years
later
that
he
completed
the
synthesis.
It
is,
alas,
impossible
to
reconstruct
his
struggle
on
the
rungs
of
Jacob's
ladder
with
the
angel
who
guards
the
secrets
of
the
cosmos
–
as
we
have
been
able
to
do
in
Kepler's
case;
for
Newton
was
not
communicative
about
the
genesis
of
his
discoveries,
and
the
scant
information
he
provides
sound
like
rationalizations
after
the
fact.
Besides,
part
of
the
thinking
was
done
collectively
by
the
circle
round
the
Royal
Society
–
Hooke,
Halley,
Christopher
Wren
–
and
influenced
by
kindred
minds
like
Huygens'
in
Holland;
so
that
it
is
impossible
to
know
precisely
which
intermediary
step
was
first
taken
by
whom.