P34: Insofar as men are torn by affects which are passions, they can be contrary to one another.

Dem.: A man—Peter, say—can be a cause of Paul’s being saddened, because he has something like a thing Paul hates (by IIIP16), or because Peter alone possesses something which Paul also loves (see IIIP32 and P32 S), or on account of other causes (for the main causes, see IIIP55 S). And so it will happen, as a result (by Def. Aff. VII), that Paul hates Peter. Hence, it will easily happen (by IIIP40 and P40 S) that Peter hates Paul in return, and so (by IIIP39) that they strive to harm one another; i.e. (by P30), that they are contrary to one another. But an affect of Sadness is always a passion (by IIIP59). Therefore, men, insofar as they are torn by affects which are passions, can be contrary to one another, q.e.d.

Schol.: I have said that Paul hates Peter because he imagines that Peter possesses what Paul himself also loves. At first glance it seems to follow from this that these two are injurious to one another because they love the same thing, and hence, because they agree in nature. If this were true, then P30 and P31 would be false.

But if we are willing to examine the matter fairly, we shall see that all these propositions are completely consistent. For these two are not troublesome to one another insofar as they agree in nature, i.e., insofar as each loves the same thing, but insofar as they disagree with one another. For insofar as each loves the same thing, each one’s love is thereby encouraged (by IIIP31). I.e. (by Def. Aff. VI), each one’s Joy is thereby encouraged. So it is far from true that they are troublesome to one another insofar as they love the same thing and agree in nature.

Instead, as I have said, the cause of {their enmity} is nothing but the fact that (as we suppose) they disagree in nature. For we suppose that Peter has the idea of a thing he loves which is already possessed, whereas Paul has the idea of a thing he loves which is lost. That is why the one is affected with Joy and the other with Sadness, and to that extent they are contrary to one another.

In this way we can easily show that the other causes of hate depend only on the fact that men disagree in nature, not on that in which they agree.