No one, however, loves his neighbour who does not out of his love to God do all in his power to bring his neighbour also, whom he loves as himself, to love God, whom if he does not love, he neither loves himself nor his neighbour. Hence it is true that if a man shall keep the whole law, and yet offend in one point, he becomes guilty of all, because he does what is contrary to the love on which hangs the whole law. A man, therefore, becomes guilty of all by doing what is contrary to that on which all hang.
Augustine, Letter 167 (chapter 5/section 16) to Jerome.
