E4P29D
Demonstration — Part IV
Latin
Cujuscunque rei singularis et consequenter (per corollarium propositionis 10 partis II) hominis potentia qua existit et operatur, non determinatur nisi ab alia re singulari (per propositionem 28 partis I) cujus natura (per propositionem 6 partis II) per idem attributum debet intelligi per quod natura humana concipitur. Nostra igitur agendi potentia quomodocunque ea concipiatur, determinari et consequenter juvari vel coerceri potest potentia alterius rei singularis quæ aliquid commune nobiscum habet et non potentia rei cujus natura a nostra prorsus est diversa et quia id bonum aut malum vocamus quod causa est lætitiæ aut tristitiæ (per propositionem 8 hujus) hoc est (per scholium propositionis 11 partis III) quod nostram agendi potentiam auget vel minuit, juvat vel coercet, ergo res cujus natura a nostra prorsus est diversa nobis neque bona neque mala esse potest. Q.E.D.
English (Elwes 1883)
The power of every individual thing, and consequently the power of man, whereby he exists and operates, can only be determined by an individual thing (I. xxviii.), whose nature (II. vi.) must be understood through the same nature as that, through which human nature is conceived. Therefore our power of activity, however it be conceived, can be determined and consequently helped or hindered by the power of any other individual thing, which has something in common with us, but not by the power of anything, of which the nature is entirely different from our own; and since we call good or evil that which is the cause of pleasure or pain (IV. viii.), that is (III. xi. note), which increases or diminishes, helps or hinders, our power of activity; therefore, that which is entirely different from our nature can neither be to us good nor bad. Q.E.D.
Modern English
The power of any individual thing — and therefore (E2P10C) the power of a human being — by which it exists and operates, is determined only by another individual thing (E1P28), whose nature (E2P6) must be understood through the same attribute as that through which human nature is conceived. Our power of acting, however it is conceived, can therefore be determined, and consequently helped or checked, only by the power of another individual thing that has something in common with us, not by the power of a thing whose nature is entirely different from ours.
And since we call something good or bad when it is the cause of joy or sadness (E4P8), that is (E3P11S), when it increases or diminishes, helps or checks, our power of acting, a thing whose nature is entirely different from ours can be neither good nor bad for us. Q.E.D.