From: Human Soul
and Its Eternal Journey
Regarding your questions
concerning the condition of the soul during illness. The passages in the
"Gleanings" make it quite clear that physical ailments, no matter how
severe, cannot bring any change in the inherent condition of the soul. As Bahá'u'lláh
says: 'The spirit is permanent and steadfast in its station'. The veil or
hindrance that interposes between soul and body during physical disease is
sickness itself. Sickness reveals itself. Sickness reveals a lack of balance in
human organism, an absence of equilibrium in the forces essential for the
normal functioning of the human body.
(From a letter written on behalf of
Shoghi Effendi to an individual believer, March 8, 1936; Lights of Guidance)