through pain or pleasure, hatred or
love, is greater in proportion as the emotion is greater.

Proof.--Pain diminishes or constrains a man's power of
activity (III. xi. note), in other words (III. vii.), diminishes
or constrains the effort, wherewith he endeavours to persist in
his own being; therefore (III. v.) it is contrary to the said
endeavour: thus all the endeavours of a man affected by pain are
directed to removing that pain. But (by the definition of pain),
in proportion as the pain is greater, so also is it necessarily
opposed to a greater part of man's power of activity; therefore
the greater the pain, the greater the power of activity employed
to remove it; that is, the greater will be the desire or
appetite in endeavouring to remove it. Again, since pleasure
(III. xi. note) increases or aids a man's power of activity, it
may easily be shown in like manner, that a man affected by
pleasure has no desire further than to preserve it, and his
desire will be in proportion to the magnitude of the pleasure.

Lastly, since hatred and love are themselves emotions of pain
and pleasure, it follows in like manner that the endeavour,
appetite, or desire, which arises through hatred or love, will be
greater in proportion to the hatred or love. Q.E.D.

PROP. XXXVIII. If a man has begun to hate an object of his love,
so that love is thoroughly destroyed, he will, causes being
equal, regard it with more hatred than if he had never loved it,
and his hatred will be in proportion to the strength of his
former love.

Proof.--If a man begins to hate that which he had loved, more
of his appetites are put under restraint than if he had never
loved it. For love is a pleasure (III. xiii. note) which a man
endeavours as far as he can to render permanent (III. xxviii.);
he does so by regarding the object of his love as present, and by
affecting it as far as he can pleasurably; this endeavour is
greater in proportion as the love is greater, and so also is the
endeavour to bring about that the beloved should return his
affection (III. xxxiii.). Now these endeavours are constrained
by hatred towards the object of love (III. xiii. Coroll. and III.
xxiii.); wherefore the lover (III. xi. note) will for this cause
also be affected with pain, the more so in proportion as his love
has been greater; that is, in addition to the pain caused by
hatred, there is a pain caused by the fact that he has loved the
object; wherefore the lover