P34: The greater the affect with which we imagine a thing we love to be affected toward us, the more we shall exult at being esteemed.

Dem.: We strive (by P33), as far as we can, that a thing we love should love us in return, i.e. (by P13 S), that a thing we love should be affected with Joy, accompanied by the idea of ourselves {as cause}. So the greater the Joy with which we imagine a thing we love to be affected on our account, the more this striving is aided, i.e. (by P11 and P11 S), the greater the Joy with which we are affected. But when we rejoice because we have affected another, like us, with Joy, then we regard ourselves with Joy (by P30).

Therefore, the greater the affect with which we imagine a thing we love to be affected toward us, the greater the Joy with which we shall regard ourselves, or (by P30 S) the more we shall exult at being esteemed, q.e.d.