In some sense the most benevolent, generous person in the world seeks his own happiness in doing good to others, because he places his happiness in their good. His mind is so enlarged as to take them, as it were, into himself. Then when they are happy, he feels it; he partakes with him, and is happy in their happiness. This is so far from being inconsistent with the freeness of benificence that, on the contrary, free benevolence and kindness consists in it.
Jonathan Edwards 1707-1758
(quoted by Piper, Desiring God, p111)