<HTML>The Schlesinger Institute for Medical-Halakahic Research dedicated a
volume of their periodical, ASSIA, to "The Concept of Old Age in Jewish
Thought." It is Volume 9 no.4 (issue #36), July-Tamuz, 1983. Apart from
the articles themselves, it contains an extensive bibliography of primary
halakhic sources on the subject.
In the Geonic period, there was a notion that life-spans were
predetermined. Some Jewish philosophers (including Sa`adiah Gaon!)
subscribed to this, but Rambam, representing the mainstream position,
denied it vigorously in one of his lengthy responsa--published as Teshuvat
haRambam biShe'elat haKeitz haKatzuv laHayyim .</HTML>
