P38: If someone begins to hate a thing he has loved, so that the Love is completely destroyed, then (from an equal cause) he will have a greater hate for it than if he had never loved it, and this hate will be the greater as the Love before was greater.

Dem.: For if someone begins to hate a thing he loves, more of his appetites will be restrained than if he had not loved it. For Love is a Joy (by P13 S), which the man, as far as he can (by P28), strives to preserve; and (by the same scholium) he does this by regarding the thing he loves as present, and by affecting it, as far as he can, with Joy (by P21). This striving (by P37) is greater as the love is greater, as is the striving to bring it about that the thing he loves loves him in return (see P33). But these strivings are restrained by hatred toward the thing he loves (by P13 C and P23); therefore, the lover (by P11 S) will be affected with Sadness from this cause also, and the more so as his Love was greater. I.e., apart from the Sadness that was the cause of the Hate, another arises from the fact that he loved the thing. And consequently he will regard the thing he loved with a greater affect of Sadness, i.e. (by P13 S), he will have a greater hatred for it than if he had not loved it. And this hate will be the greater as the love was greater, q.e.d.