9. Look, there lies a deep truth in what has been said so far, for the light of the sun carries purer spirits with it, as you can well imagine. These spirits are closely related to the substantial parts of the human soul. When the soul is strengthened through the influence of such pure spirits it can easily and quickly overcome some weakness in its body, since the health of the body always solely depends on a sufficiently strong soul.
10. Wherever some weakness first appears in the substantial parts of the soul and the soul is unable to gain strength for these weakened parts in a proper way, it resorts to its own nerve essence, drawing from it what it lacks. The result is, as in discharged electrical bottles an obvious shortage in the nerves, of the life fluidum through which alone the right current is sustained.