E4P37D
Demonstration — Part IV
Latin
Homines quatenus ex ductu rationis vivunt, sunt homini utilissimi (per corollarium I propositionis 35 hujus) atque adeo (per propositionem 19 hujus) ex ductu rationis conabimur necessario efficere ut homines ex ductu rationis vivant. At bonum quod unusquisque qui ex rationis dictamine vivit hoc est (per propositionem 24 hujus) qui virtutem sectatur, sibi appetit, est intelligere (per propositionem 26 hujus); ergo bonum quod unusquisque qui virtutem sectatur, sibi appetit, reliquis hominibus etiam cupiet. Deinde cupiditas quatenus ad mentem refertur, est ipsa mentis essentia (per 1 affectuum definitionem); mentis autem essentia in cognitione consistit (per propositionem 11 partis II) quæ Dei cognitionem involvit (per propositionem 47 partis II) et sine qua (per propositionem 15 partis I) nec esse nec concipi potest adeoque quo mentis essentia majorem Dei cognitionem involvit, eo cupiditas qua is qui virtutem sectatur, bonum quod sibi appetit, alteri cupit, etiam major erit. Q.E.D.
English (Elwes 1883)
Men, in so far as they live in obedience to reason, are most useful to their fellow men (IV. xxxv; Coroll. i.); therefore (IV. xix.), we shall in obedience to reason necessarily endeavour to bring about that men should live in obedience to reason. But the good which every man, in so far as he is guided by reason, or, in other words, follows after virtue, desires for himself, is to understand (IV. xxvi.); wherefore the good, which each follower of virtue seeks for himself, he will desire also for others. Again, desire, in so far as it is referred to the mind, is the very essence of the mind (Def. of the Emotions, i.); now the essence of the mind consists in knowledge (II. xi.), which involves the knowledge of God (II. xlvii.), and without it (I. xv.), can neither be, nor be conceived; therefore, in proportion as the mind's essence involves a greater knowledge of God, so also will be greater the desire of the follower of virtue, that other men should possess that which he seeks as good for himself. Q.E.D.
Another Proof.--The good, which a man desires for himself and loves, he will love more constantly, if he sees that others love it also (III. xxxi.); he will therefore endeavour that others should love it also; and as the good in question is common to all, and therefore all can rejoice therein, he will endeavour, for the same reason, to bring about that all should rejoice therein, and this he will do the more (III. xxxvii.), in proportion as his own enjoyment of the good is greater.
Modern English
Human beings, in so far as they live under the guidance of reason, are maximally useful to one another (E4P35C1). We shall therefore necessarily strive, under the guidance of reason (E4P19), to bring it about that human beings live under the guidance of reason. Now, the good that every person who lives according to reason, that is (E4P24), who follows after virtue, seeks for himself is to understand (E4P26). The good that each follower of virtue seeks for himself, then, he will also desire for others.
Further, desire, in so far as it is referred to the mind, is the very essence of the mind (E3DA1). The essence of the mind consists in knowledge (E2P11), which involves the knowledge of God (E2P47) and without which it can neither exist nor be conceived (E1P15). Therefore, in proportion as the mind's essence involves a greater knowledge of God, so too will be greater the desire by which one who follows virtue wishes for another what he seeks as good for himself. Q.E.D.