I would first like to say that, in my view, Seth did NOT give a final and definitive explanation for the fact that Jane chose to create a reality in which she suffered from the chronic and disabling illness of rheumatoid arthritis. If she had developed the illness 20 years later, more effective treatments may have been available.
That Jane's illness “grow out of her mystical nature” is more Rob's idea than specifically Seth's. This is the relevant extract from DEAVF1:
“Once again I note that in my opinion Jane's dependency represents, at
least in part, a search for a "redemption" that encompasses other
motivations and realities than those concerned with "just" our temporal
lives; that indeed, her impaired state grew out of her mystical nature
itself (but was hardly caused by it!).
So, although I think that Jane has made some "remarkable gains"
during recent weeks, I also think that basically she has yet to resolve
the entire issue of her illnesses—or even whether to continue physical
life. Seth put it beautifully a couple of months ago in the session for
April 12—the first time Jane spoke for him since leaving the hospital—
and I return to it again and again. See the essay for April 16: "
The
entire issue (of Jane's living) had been going on for some time, and the
argument— the argument being somewhat in the nature of a soul facing
its own legislature, or perhaps standing as a jury before itself, setting its
own case in a kind of private yet public psychic trial. Life decisions are
often made in just such a fashion. With Ruburt they carried a psychic
and physical logic and economy. . . ."Obviously, Jane's deliberations over whether to continue physical life
are much easier to appreciate when she's depressed and/ or physically
uncomfortable, and during those times I can sense the fluctuations in
her examination of her psyche. Portions of her are still quite
deliberately thinking it all over, I'm sure, although she doesn't mention
this outside the session frameworks she provides for Seth and herself.”
There is an interesting article on rheumatoid arthritis here:
https://curearthritis.org/arthritis-archives-rheumatoid-arthritis/“1980 saw considerable strides being made in the treatment of RA by the use of a drug developed for chemotherapy in the 1950s – methotrexate. This drug revolutionised RA therapeutics, most patients that received the drug responded well with good control of joint inflammation. This was a game changer and led to a great reduction in patients having to undergo joint replacement or other orthopaedic surgeries.”