is (III. xi.),
the body's power of activity is increased or aided in such a
manner, that the several parts maintain their former proportion
of motion and rest; therefore Mirth is always good (IV. xxxix.),
and cannot be excessive. But Melancholy (see its Def. in the
same note to III. xi.) is pain, which, in so far as it is
referred to the body, consists in the absolute decrease or
hindrance of the body's power of activity; therefore (IV.
xxxviii.) it is always bad. Q.E.D.

PROP. XLIII. Stimulation may be excessive and bad; on the other
hand, grief may be good, in so far as stimulation or pleasure is
bad.

Proof.--Localized pleasure or stimulation (titillatio) is
pleasure, which, in so far as it is referred to the body,
consists in one or some of its parts being affected more than the
rest (see its Definition, III. xi. note); the power of this
emotion may be sufficient to overcome other actions of the body
(IV. vi.), and may remain obstinately fixed therein, thus
rendering it incapable of being affected in a variety of other
ways: therefore (IV. xxxviii.) it may be bad. Again, grief,
which is pain, cannot as such be good (IV. xli.). But, as its
force and increase is defined by the power of an external cause
compared with our own (IV. v.), we can conceive infinite degrees
and modes of strength in this emotion (IV. iii.); we can,
therefore, conceive it as capable of restraining stimulation, and
preventing its becoming excessive, and hindering the body's
capabilities; thus, to this extent, it will be good. Q.E.D.

PROP. XLIV. Love and desire may be excessive.

Proof.--Love is pleasure, accompanied by the idea of an
external cause (Def. of Emotions, vi.); therefore stimulation,
accompanied by the idea of an external cause is love (III. xi.
note); hence love maybe excessive. Again, the strength of
desire varies in proportion to the emotion from which it arises
(III. xxxvii.). Now emotion may overcome all the rest of men's
actions (IV. vi.); so, therefore, can desire, which arises from
the same emotion, overcome all other desires, and become
excessive, as we showed in the last proposition concerning
stimulation.

Note.--Mirth, which I have stated to be good, can be conceived
more easily than it can be observed. For the emotions, whereby
we are daily assailed, are generally referred to some part of the
body which is affected more than the rest; hence the emotions
are generally excessive, and so fix the mind i