E4P44D
Demonstration — Part IV
Latin
Amor est lætitia (per definitionem 6 affectuum) concomitante idea causæ externæ; titillatio igitur (per scholium propositionis 11 partis III) concomitante idea causæ externæ amor est atque adeo amor (per propositionem præcedentem) excessum habere potest. Deinde cupiditas eo est major quo affectus ex quo oritur major est (per propositionem 37 partis III). Quare ut affectus (per propositionem 6 hujus) reliquas hominis actiones superare potest, sic etiam cupiditas quæ ex eodem affectu oritur, reliquas cupiditates superare ac proinde eundem excessum habere poterit quem in præcedenti propositione titillationem habere ostendimus. Q.E.D.
English (Elwes 1883)
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.
Modern English
Love is joy accompanied by the idea of an external cause (E3DA6). Localized pleasure accompanied by the idea of an external cause is therefore love (E3P11S), and so love can have excess (E4P43). Now desire grows in proportion to the affect from which it arises (E3P37). An affect can overwhelm all the rest of a person's actions (E4P6), and so desire arising from that affect can likewise overwhelm all other desires and have the same excess that we showed localized pleasure to have in the preceding proposition. Q.E.D.