Note.- This is also self-evident; for, if we say that white and black only agree in the fact that neither is red, we absolutely affirm that the do not agree in any respect. So, if we say that a man and a stone only agree in the fact that both are finite - wanting in power, not existing by the necessity of their own nature, or, lastly, indefinitely surpassed by the power of external causes - we should certainly affirm that a man and a stone are in no respect alike; therefore, things which agree only in negation, or in qualities which neither possess, really agree in no respect.
Prop. XXXIII. Men can differ in nature, in so far as they are assailed by those emotions, which are passions, or passive states; and to this extent one and the same man is variable and inconstant.
Proof.- The nature or essence of the emotions cannot be explained solely through our essence or nature (III:Def.i.&ii.), but it must be defined by the power, that is (III:vii.), by the nature of external causes in comparison with our own; hence it follows, that there are as many kinds of each emotion as there are external objects whereby we are affected (III:lvi.), and that men may be differently affected by one and the same object (III:li), and to this extent differ in nature; lastly, that one and the same man may be differently affected towards the same object, and may therefore be variable and inconstant. Q.E.D.
Prop. XXXIV. In so far as men are assailed by emotions which are passions, they can be contrary one to another.
Proof.- A man, for instance Peter, can be the cause of Paul's feeling pain, because he (Peter) possesses something similar to that which Paul hates (III:xvi.), or because Peter has sole possession of a thing which Paul also loves (III:xxxii.&Note), or for other causes (of which the chief are enumerated in III:lv.Note); it may therefore happen that Paul should hate Peter (Def. of Emotions: vii.), consequently it may easily happen also, that Peter should hate Paul in return, and that each should endeavour to do the other an injury, (III:xxxix.), that is (IV:xxx.), that they should be contrary one to another. But the emotion of pain is always a passion or passive state (III:lix.); hence men, in so far as they are assailed by emotions which are passions, can be contrary one to another. Q.E.D.
Note.- I said that Paul may hate Peter, because he conceives that Peter possesses something which he (Paul) also loves; from this it seems, at first sight, to follow, that these two men, through both loving the same thing, and, consequently, through agreement of their respective natures, stand in one another's way; if this were so, II:xxx. and II:xxxi. would be untrue.
But if we give the matter our unbiased attention, we shall see that the discrepancy vanishes. For the two men are not in one another's way in virtue of the agreement of their natures, that is, through both loving the same thing, but in virtue of one differing from the other. For, in so far as each loves the same thing, the love of each is fostered thereby (III:xxxi.), that is (Def. of the Emotions: vi.) the pleasure of each is fostered thereby. Wherefore it is far from being the case, that they are at variance through both loving the same thing, and through the agreement in their natures. The cause for their opposition lies, as I have said, solely in the fact that they are assumed to differ. For we assume that Peter has the idea of the loved object as already in his possession, while Paul has the idea of the loved object as lost. Hence the one man will be affected with pleasure, the other will be affected with pain, and thus they will be at variance one with another. We can easily show in like manner, that all other causes of hatred depend solely on differences, and not on the agreement between men's natures.
Prop. XXXV. In so far only as men live in obedience to reason, do they always necessarily agree in nature.
Proof.- In so far as men are assailed by emotions that are passions, they can be different in nature (IV:xxxiii.), and at variance one with another.
But men are only said to be active, in so far as they act in obedience to reason (III:iii.); therefore, what so ever follows from human nature in so far as it is defined by reason must (III:Def.ii.) be understood solely through human nature as its proximate cause. But, since every man by the laws of his nature desires that which he deems good, and endeavours to remove that which he deems bad (IV:xix.); and further, since that which we, in accordance with reason, deem good or bad, necessarily is good or bad (II:xli.); it follows that men, in so far as they live in obedience to reason, necessarily do only such things as are necessarily good for human nature, and consequently for each individual man (IV:xxxi.Coroll.); in other words, such things as are in harmony with each man's nature.
Therefore, men in so far as they live in obedience to reason, necessarily live always in harmony one with another. Q.E.D.
Corollary I - There is no individual thing in nature, which is more useful to man, than a man who lives in obedience to reason. For that thing is to man most useful, which is most in harmony with his nature (IV:xxxi.Coroll.); that is, obviously, man. But man acts absolutely according to the laws of his nature, when he lives in obedience to reason (III:Def.ii.), and to this extent only is always necessarily in harmony with the nature of another man (by the last Prop.); wherefore among individual things nothing is more useful to man, than a man who lives in obedience to reason. Q.E.D.
