216 DOCS.
222,
223 MAY 1916
We
are
expecting you, therefore,
for
the
19th
of
June
and
hope
that
yon
stay
the
entire week
so
that
we
can
go on an
excursion with
you.
There
is
a
very
pleasant
and also
politically very inspired
and interested circle here.
With
most cordial
regards, yours,
D. Hilbert.
223.
To
David Hilbert
[Berlin,]
30
May
1916
Dear
Colleague,
Your
invitation
to
the
Smoluchowski
event[1] tempts
me very
much,
especially
considering
that the
fine
days
spent
with
you
have
stayed
with
me as a
dear
memory.[2]
I
cannot
promise yet
to
come,
because
I
am
tied down
quite
inextri-
cably
here
by
various
ongoing
commitments.
But
in
any case,
this
time
I
would
stay
at
an
inn,
if
only
not
to
appear
to
myself
as a
nuisance.
I
also find Schwarzschild’s
death
distressing.[3]
Among
the
living
there
are
probably
only
a
few
who know
how
to
apply
mathematics with
such
a
virtuosity
as
his.
Your
explanation of
equation
(6)
of
your
paper[4] was
charming. Why
do
you
make it
so
hard
for
poor
mortals
by withholding
the
technique
behind
your
ideas?
It
surely
does
not
suffice
for
the
thoughtful
reader
if, although
able to
verify
the
correctness
of
the
equations,
he cannot have
a
clear view
of
the
overall
plan
of
the
analysis.
In
the
Freundlich affair
a
turn
for
the better
seems
to
be in
the
making,
thank
heavens.[5]
Fr. went
to
see
Küstner
in
Bonn.[6]
The
latter
received him
very
ami-
cably
and
is prepared to support
him in
every
way.
If
Küstner
came
to
Potsdam
as
Schwarzschild’s
successor,[7] a
conscientious examination of
the
experimental
gravitation
questions
would
then
be
safeguarded,
and
simultaneously
Freundlich
would be saved from
a
situation that
has become
positively heartrending.[8]
I
have
written
a
letter
to
Naumann,
in order to
place my
bit of
weight on
the
scale toward
the
above.[9] For,
if
Hartmann
were
to
come
to
Potsdam,
it would
be
disastrous.[10]
(Anyway,
how could
you possibly
find
the
strength
to
console
yourself
about the
separation?)
In
your paper everything
is
understandable
to
me now
except
for
the
energy
theorem. Please do not
be
angry
with
me
that
I
ask
you
about
this
again.[11]
My
difficulty
consists in
the
following:
In
your
equation[12]
EdVge'/dx'=0