If we conceive that anything pleasurably affects some object of our love, we shall be affected with love towards that thing.

Contrariwise, if we conceive that it affects an object of our love painfully, we shall be affected with hatred towards it.
Proof .-- He, who affects pleasurably or painfully the object of our love, affects us also pleasurably or painfully--that is, if we conceive the loved object as affected with the said pleasure or pain (III.

xxi.).

But this pleasure or pain is postulated to come to us accompanied by the idea of an external cause; therefore (III.xiii.

note), if we conceive that anyone affects an object of our love pleasurably or painfully, we shall be affected with love or hatred towards him.