Saint Augustine of Hippo

Whoever, then, loves his neighbor aright, ought to urge upon him that he too should love God with his whole heart, and soul, and mind. For in this way, loving his neighbor as himself, a man turns the whole current of his love both for himself and his neighbor into the channel of the love of God, which suffers no stream to be drawn off from itself by whose diversion its own volume would be diminished. 

-- Saint Augustine of Hippo