E4P63D2
Demonstration — Part IV
Latin
Nam cupiditas quæ ex ratione oritur, ex solo lætitiæ affectu quæ passio non est, oriri potest (per propositionem 59 partis III) hoc est ex lætitia quæ excessum habere nequit (per propositionem 61 hujus) non autem ex tristitia ac proinde hæc cupiditas (per propositionem 8 hujus) ex cognitione boni, non autem mali oritur atque adeo ex ductu rationis bonum directe appetimus et eatenus tantum malum fugimus. Q.E.D.
English (Elwes 1883)
Desire which springs from reason can only spring from a pleasurable emotion, wherein the mind is not passive (III. lix.), in other words, from a pleasure which cannot be excessive (IV. lxi.), and not from pain; wherefore this desire springs from the knowledge of good, not of evil (IV. viii.); hence under the guidance of reason we seek good directly and only by implication shun evil. Q.E.D.
Modern English
Desire that arises from reason can only arise from joy that is not a passion (E3P59) — that is, from joy that cannot be excessive (E4P61) — and not from sadness. Therefore this desire arises from knowledge of the good, not of the bad (E4P8). Hence under the guidance of reason we seek good directly and shun bad only to that extent. Q.E.D.