E3P37D
Demonstration — Part III
Latin
Tristitia hominis agendi potentiam (per scholium propositionis 11 hujus) minuit vel coercet hoc est (per propositionem 7 hujus) conatum quo homo in suo esse perseverare conatur, minuit vel coercet adeoque (per propositionem 5 hujus) huic conatui est contraria et quicquid homo tristitia affectus conatur, est tristitiam amovere. At (per tristitiæ definitionem) quo tristitia major est, eo majori parti hominis agendi potentiæ necesse est opponi; ergo quo major tristitia est, eo majore agendi potentia conabitur homo contra tristitiam amovere hoc est (per scholium propositionis 9 hujus) eo majore cupiditate sive appetitu conabitur tristitiam amovere. Deinde quoniam lætitia (per idem scholium propositionis 11 hujus) hominis agendi potentiam auget vel juvat, facile eadem via demonstratur quod homo lætitia affectus nihil aliud cupit quam eandem conservare idque eo majore cupiditate quo lætitia major erit. Denique quoniam odium et amor sunt ipsi tristitiæ vel lætitiæ affectus, sequitur eodem modo quod conatus, appetitus sive cupiditas quæ præ odio vel amore oritur, major erit pro ratione odii et amoris. Q.E.D.
English (Elwes 1883)
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.
Modern English
Sadness diminishes or checks a person's power of acting (E3P11S), that is (E3P7), it diminishes or checks the striving by which a person endeavors to persevere in his being, and so (E3P5) it is contrary to that striving. Whatever a person affected with sadness strives for is to remove that sadness. Now by the definition of sadness, the greater the sadness, the greater the part of a person's power of acting it necessarily opposes. Therefore the greater the sadness, the greater the power of acting with which the person will strive to remove it, that is (E3P9S), the greater the desire or appetite with which he will strive to remove sadness.
Since joy (E3P11S) increases or aids a person's power of acting, it can be shown by the same reasoning that a person affected with joy desires nothing other than to preserve it, and this with desire in proportion to the joy.
Finally, since hatred and love are themselves affects of sadness and joy, it follows in the same way that striving, appetite, or desire arising from hatred or love is greater in proportion to the hatred and love. Q.E.D.