T 2.2.6.6

We may, therefore, infer, that benevolence and anger are passions different from love and hatred, and only conjoin'd with them, by the original constitution of the mind. As nature has given to the body certain appetites and inclinations, which she encreases, diminishes, or changes according to the situation of the fluids or solids; she has proceeded in the same manner with the mind. According as we are possess'd with love or hatred, the correspondent desire of the happiness or misery of the person, who is the object of these passions, arises in the mind, and varies with each variation of these opposite passions. This order of things, abstractedly consider'd, is not necessary. Love and hatred might have been unattended with any such desires, or their particular connexion might have been entirely revers'd. If nature had so pleas'd, love might have had the same effect as hatred, and hatred as love. I see no contradiction in supposing a desire of producing misery annex'd to love, and of happiness to hatred. If the sensation of the passion and desire be opposite, nature cou'd have alter'd the sensation without altering the tendency of the desire, and by that means made them compatible with each other.