6. Sometimes two opposing mistresses have possession of a man, avarice and luxuriousness. Avarice says, “Keep;” luxuriousness, says, “Spend.” Under two mistresses bidding and exacting diverse things what can you do? They have both their mode of address. And when you begin to be unwilling to obey them, and to take a step towards your liberty; because they have no power to command, they use caresses. Their caresses are more to be guarded against than their commands.
What says avarice? “Keep for yourself, keep for your children. If you should be in want, no one will give to you. Live not for the time present only; consult for the future.”
On the other hand is luxuriousness. Live while you may. Do good to your own soul. Die you must, and you know not when; you know not to whom you shall leave what you have, or who shall possess it. You are taking the bread out of your own mouth, and perhaps after your death your heir will not so much as place a cup of wine upon your tomb; or if so be he place a cup, he will drink himself drunk with it, not a drop will come down to you. Do well therefore to your own soul, when and while you can.
Thus avarice did enjoin one thing; “Keep for yourself, consult for the future.” Luxuriousness another, “Do well to your own soul.”
7. But O free man, called unto liberty, be weary, be weary of your servitude to such mistresses as these. Acknowledge your Redeemer, your Deliverer. Serve Him, He enjoins easier things, He enjoins not things contrary one to another.
I am bold further to say; avarice and luxuriousness did enjoin upon you contrary things, so that you could not obey them both; and one said, “Keep for yourself, and consult for the future;” the other said, “Spend freely, do well to your own soul.” Now let your Lord and your Redeemer come forth, and He shall say the same, and yet no contrary things. If you will not, His house has no need of an unwilling servant.
Consider your Redeemer, consider your Ransom. He came to redeem you, He shed His Blood. Dear He held you whom He purchased at so dear a price. Thou dost acknowledge Him who bought you, consider from what He redeems you. I say nothing of the other sins which lord it proudly over you; for you were serving innumerable masters. I speak only of these two, luxuriousness and avarice, giving you contrary injunctions, hurrying you into different things. Deliver yourself from them, come to your God.”
Augustine of Hippo (354-430) from Sermon on the New Testament 36.6-7.