Consider, moreover, that he did not say, “Nobody can have God and wealth,” but “no one can be a servant of God and wealth.” It is one thing to have wealth and quite another to serve wealth. If you have wealth and your wealth does not make you haughty or violent, but you give to the poor as much as you can, you are master of your wealth, not its slave, because your wealth does not possess you, but you possess your wealth. But if your wealth makes you arrogant or violent and you do not give anything to anyone because you have been restrained by your greed, then you are a slave of your wealth and not its master, because your wealth possesses you, not you your wealth.
Opus imperfectum on Matthew, Homily XVI
Locus Communis 