Corollary II.- As every man seeks most that which is useful to him, so are men most useful one to another. For the more a man seeks what is useful to him and endeavours to preserve himself, the more is he endowed with virtue (IV:xx.), or, what is the same thing (IV:Def.viii.), the more is he endowed with power to act according to the laws of his own nature, that is to live in obedience to reason. But men are most in natural harmony, when they live in obedience to reason (by the last Prop.); therefore (by the foregoing Coroll.) men will be most useful one to another, when each seeks most that which is useful to him. Q.E.D.
Note.- What we have just shown is attested by experience so conspicuously, that it is in the mouth of nearly everyone: "Man is to man a God." Yet it rarely happens that men live in obedience to reason, for things are so ordered among them, that they are generally envious and troublesome one to another. Nevertheless they are scarcely able to lead a solitary life, so that the definition of man as a social animal has met with general assent; in fact, men do derive from social life much more convenience than injury. Let satirists then laugh their fill at human affairs, let theologians rail, and let misanthropes praise to their utmost the life of untutored rusticity, let them heap contempt on men and praises on beasts; when all is said, they will find that men can provide for their wants much more easily by mutual help, and that only by uniting their forces can they escape from the dangers that on every side beset them: not to say how much more excellent and worthy of our knowledge it is, to study the actions of men than the actions of beasts. But I will treat of this more at length elsewhere.
Prop. XXXVI. The highest good of those who follow virtue is common to all, and therefore all can equally rejoice therein.
Proof.- To act virtuously is to act in obedience with reason (IV:xxiv.), and whatsoever we endeavour to do in obedience to reason is to understand (IV:xxvi.); therefore (IV:xxviii.) the highest good for those who follow after virtue is to know God; that is (II:xlvii.&Note) a good which is common to all and can be possessed. by all men equally, in so far as they are of the same nature. Q.E.D.
Note.- Someone may ask how it would be, if the highest good of those who follow after virtue were not common to all? Would it not then follow, as above (IV:xxxiv.), that men living in obedience to reason, that is (IV:xxxv.), men in so far as they agree in nature, would be at variance one with another? To such an inquiry, I make answer, that it follows not accidentally but from the very nature of reason, that main's highest good is common to all, inasmuch as it is deduced from the very essence of man, in so far as defined by reason; and that a man could neither be, nor be conceived without the power of taking pleasure in this highest good. For it belongs to the essence of the human mind (II:xlvii.), to have an adequate knowledge of the eternal and infinite essence of God.
Prop. XXXVII. The good which every man, who follows after virtue, desires for himself he will also desire for other men, and so much the more, in proportion as he has a greater knowledge of God.
Proof.- 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 (III: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.
