3p57d.md (1322B)
1 This proposition is evident from Ax. i. (which see 2 after Lemma iii. Prop. xiii., Part II.). Nevertheless, we will 3 prove it from the nature of the three primary emotions. 4 5 All emotions are attributable to desire, pleasure, or pain, 6 as their definitions above given show. But desire is each man's 7 nature or essence (III. ix. note); therefore desire in one 8 individual differs from desire in another individual, only in so 9 far as the nature or essence of the one differs from the nature 10 or essence of the other. Again, pleasure and pain are passive 11 states or passions, whereby every man's power or endeavour to 12 persist in his being is increased or diminished, helped or 13 hindered (III. xi. and note). But by the endeavour to persist in 14 its being, in so far as it is attributable to mind and body in 15 conjunction, we mean appetite and desire (III. ix. note); 16 therefore pleasure and pain are identical with desire or 17 appetite, in so far as by external causes they are increased or 18 diminished, helped or hindered, in other words, they are every 19 man's nature; wherefore the pleasure and pain felt by one man 20 differ from the pleasure and pain felt by another man, only in so 21 far as the nature or essence of the one man differs from the 22 essence of the other; consequently, any emotion of one 23 individual only differs, &c. Q.E.D. 24 25