3p21d.md (991B)
1 The images of things (as we showed in III. xix.) which 2 postulate the existence of the object of love, help the mind's 3 endeavour to conceive the said object. But pleasure postulates 4 the existence of something feeling pleasure, so much the more in 5 proportion as the emotion of pleasure is greater; for it is 6 (III. xi. note) a transition to a greater perfection; therefore 7 the image of pleasure in the object of love helps the mental 8 endeavour of the lover; that is, it affects the lover 9 pleasurably, and so much the more, in proportion as this emotion 10 may have been greater in the object of love. This was our first 11 point. Further, in so far as a thing is affected with pain, it 12 is to that extent destroyed, the extent being in proportion to 13 the amount of pain (III. xi. note); therefore (III. xix.) he who 14 conceives, that the object of his love is affected painfully, 15 will himself be affected painfully, in proportion as the said 16 emotion is greater or less in the object of love. Q.E.D. 17 18