E4P69D
Demonstration — Part IV
Latin
Affectus coerceri nec tolli potest nisi affectu contrario et fortiore affectu coercendo (per propositionem 7 hujus). At cæca audacia et metus affectus sunt qui æque magni possunt concipi (per propositiones 5 et 3 hujus). Ergo æque magna animi virtus seu fortitudo (hujus definitionem vide in scholio propositionis 59 partis III) requiritur ad audaciam quam ad metum coercendum hoc est (per definitiones 40 et 41 affectuum) homo liber eadem animi virtute pericula declinat qua eadem superare tentat. Q.E.D.
English (Elwes 1883)
Emotion can only be checked or removed by an emotion contrary to itself, and possessing more power in restraining emotion (IV. vii.). But blind daring and fear are emotions, which can be conceived as equally great (IV. v. and iii.): hence, no less virtue or firmness is required in checking daring than in checking fear (III. lix. note); in other words (Def. of the Emotions, xl. and xli.), the free man shows as much virtue, when he declines dangers, as when he strives to overcome them. Q.E.D.
Modern English
An affect can only be checked or removed by a contrary affect that is stronger (E4P7). But blind daring and fear are affects that can be conceived as equally great (E4P5)(E4P3). Therefore an equally great strength of mind — that is, virtue (*fortitudo*) (E3P59S) — is required to check daring as to check fear. In other words (E3DA40)(E3DA41), the free man declines dangers with the same strength of mind with which he attempts to overcome them. Q.E.D.