314
DOCS.
322,
323
APRIL
1917
My
burning
desire to
see
you
and
my
other
colleagues
and
mindmates
more
often
will
assure
my coming
back to Holland
soon.[3]
This
summer
I must
first
go
to Switzerland,
though,
to be
together
with
my
children, perhaps
also to
spend
time at
a
health
resort in
Tarasp.[4] However,
my
next
trip will
certainly
take
me
to all of
you.
I
am
pleased
that
Planck and
Waldeyer
have written
you.[5]
The latter
still
hails from
the
good
old
pre-Treitschke
days.[6]
Planck did
not
tell
me
that
he
had
written
you
at
all;
that
is
why
I
feared he
had
neglected
to
do
so.
The
younger
ones are
considerably
worse
than
they,
however.
I
am
convinced
that
a
kind of
mental
epidemic
is
involved. For otherwise
I cannot
grasp why people
who
are
thoroughly
decent in
their
personal
attitudes
take
on
such
an
entirely
different
view
with
respect
to
public
affairs. I
can
only
draw
comparison
with
the
times of
martyrdom, crusades,
and witchcraft trials.
Only very
uncommon
independent
characters
can
escape
the
pressure
of
prevailing opinion.
There
seems
to
be
no
such
person
at
the
Academy.[7]
Your
joint
paper
with
Droste
is
very
interesting.[8]
It
is
splendid
that
in
L
only
first derivatives
occur
according
to time. This
is
analogous
to Hamilton’s
function of the
gravitational
field.
It
is
a
pity
that
the deviations from Newton
are
so
small;
but
ultimately,
we
ought
to
be
glad
that
Mercury’s
case
has
presented
itself,
at least.[9]
My
last
paper
will not appeal to
you.[10]
It
is
convincing only
if
the
relativity
of
inertia
is
considered
a
requirement,
that
is,
if
one
is convinced
that inertia
can
be
attributed
entirely
to
an
interaction with
the
observed
mass.[11]
Healthwise I
am
feeling
considerably
better
again,
thanks
especially
to
the
meticulous diet which
my
relatives here have been able
to provide
with
the
help
of
their southern
German connections.[12]
Without this
help
I
would
scarcely
be
able to stay
here;
I
do
not
know either whether it
can
continue
on
like
this.[13]
Affectionate
greetings
also
to
your
wife
and
the
two
de
Haases, yours,
A.
Einstein.
323. To
Felix Klein
[Berlin,]
4 April 1917
Highly
esteemed
Colleague,
Thank
you very
much for
your
kind and
interesting
letter.
I
shall not fail
to
read
your
mentioned
papers
in
the
original.[1]
That
which
you
call
agnostic
in
your position
is
present
also
in
mine, specifically,
in
the
following
form:
No
matter how
we
draw
a
complex
from
nature
for
simplicity’s
sake,
its theoretical