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