e its effects on the body, though there can be no
doubt, that the body is under the influence of its stimulus, and
powerfully excited by it; for when it is diminished, or cold applied,
we feel a deficiency of excitement, and become afterwards more
sensible of heat afterwards applied.

The same takes place with respect to joy and grief, and proves, I
think, clearly, that the one is only a diminution of the other, and
that they are not different passions. When the body has been exposed
to severe cold, the excitability becomes so much accumulated with
respect to heat, that if it be afterwards applied too powerfully, a
violent action, with a rapid exhaustion of the excitability, which
ends in mortification, or death of the part, will take place. We
should therefore apply heat in the gentlest manner possible, and
gradually exhaust the morbidly accumulated excitability.

In the same manner, when the body has been under the influence of
violent grief, any sudden joy has been known to overpower the system,
and even produce instant death. We have an instance in history, of a
mother being plunged into the extreme of grief, on being informed
that her son was slain in battle; but when news was brought her, that
he was alive, and well, the effect upon her spirits was such, as to
bring on instant death. This event ought to have been unfolded to her
in the most gradual manner; she should have been told, for instance,
that he was severely wounded; but that it was not certain he was
dead; then that there was a report he was living, which should have
been gradually confirmed, as she could bear it. The same observations
may be made, with respect to hope and fear, or despair; the former is
an exciting passion, the latter, a depressing one; but the one is
only a lower degree of the other; for a moderate degree of hope
produces a pleasant state of serenity of the mind, and contributes to
the health of the body; but a diminution of it weakens; and a great
degree of despair so accumulates the excitability of the system, as
to render it liable to be overpowered by any sudden hope or joy
afterwards applied. What proves that joy and hope act by stimulating,
and grief and despair by withdrawing stimulant action from the body,
is, that the former exhaust excitability, while the latter accumulate
it. Joy, for instance, does not render the system more liable to be
affected by hope, but the reverse; and the same may be said of hope.
In the same way,