r, 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, Props. xxx. and xxxi. of this part 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 (