Dear Marion,

Thank you for your letter. I am impressed and much pleased with
the aplomb with which you manage the complexities in which nature,
with the help of the doctors, has enmeshed you. I very much hope
that your confidence and determination will not forsake you. As
I've promised, I will try hard not to make matters difficult for
you, and will provide you with whatever help I can.

By now you should be accustomed to my scepticism. I read the
display of the pulse oximeter as a set of numbers to which one
should not attach magical significance. What they mean can only be
determined by observation and experiment. I remember vividly one
of my father's most embarrasing mistakes in his practice. The
patient was a woman who cam from some distance, attracted by
my father's reputation and charisma. She felt in good health;
her complaint was FUO, fever of unknown origin. My father, who
prided himself in his diagnostic diligence, performed all manner
of tests, X-rays, blood examinations, until in the end he 
identified antibodies to some rare textbook disease which none
of us had ever observed and for which there was no treatment.
I remember no details, except that the patient who until then
had felt well, was distressed to be told she was afflicted with
an illness for which there was no treatment ... In retrospect
I see a mistake of my father's whose thinking was too inflexible
to acknowledge the artificiality of medical diagnoses. But that
said, I believe the quality of his practice was far above "average".

I have been reflecting on the neurological basis of the perception
of pain, on the role of "endorphins" in mitigating, modulating and
possibly amplifying pain "impulses" from peripheral nerves. In this
context, I've been thinking also  about the "central control" of
respiration, asking myself whether your intermittent shortness of
breath and the oxy-hemoglobin saturation on the low side of normal
might reflect some minor and perhaps innocuous calibration error
in your "pneumostat", if you permit me this neologism. The relevant
references are:
http://en.wikipedia.org/wiki/Control_of_respiration
http://en.wikipedia.org/wiki/Respiratory_center
As usual, I offer only questions, no answers.

Margaret and I plan to leave Konnarock on Monday July 11, arriving
in Belmont in late afternoon on July 12. Unless I have a message
from you, or perhaps an inspired thought demanding immediate
expression, I'll probably not write again until the middle of
next week. I wish you a satisfactory weekend on the Farm and ask
that you keep me informed.

Jochen