Liberality to the poor is recommended by the example of the widow the Gospel, whose two mites were preferred to the large gifts of the rich. The two mites are treated as mystically representing the two Testaments. What that treasure is for which we are taught to offer, after the example of the wise men, three gifts, or after that of the widow, two. St. Ambrose concludes the chapter by an exhortation to widows to be zealous in good works.
27. In the same book, too, but in another place, we are taught how fitting it is to be merciful and liberal towards the poor, and that this feeling should not be checked by the consideration of our poverty, since liberality is determined not by the amount of our possessions, but by the disposition of giving. For by the voice of the Lord that widow is preferred to all of whom it was said: “This widow has cast in more than all.” In which instance the Lord characteristically teaches all, that none should be held back from giving assistance through shame at his own poverty, and that the rich should not flatter themselves that they seem to give more than the poor. For the piece of money out of a small stock is richer than treasures out of abundance, because it is not the amount that is given but the amount that remains which is considered. No one gives more than she who has left nothing for herself.
28. Why do you, rich woman, boast yourself by comparison with the poor, and when you are all loaded with gold, and drag along the ground a costly robe, desire to be honoured as though she were inferior and small in comparison with your riches, because you have surpassed the needy with your gifts? Rivers too overflow, when they are too full, but a draught from a brook is more pleasant. New wine foams while fermenting, and the husbandman does not consider as lost that which runs over. While the harvest is being threshed out, grains of grain fall from the groaning floor; but though the harvests fail, the barrel of meal wastes not, and the cruse full of oil gives forth. But the draught emptied the casks of the rich, while the tiny cruse of oil of the widow gave abundance. That, then, is to be reckoned which you give for devotion, not what you cast forth disdainfully. For in fine, no one gave more than she who fed the prophet with her children's nourishment. And so since no one gave more, no one had greater merit. This has a moral application.
29. And considering the mystical sense, one must not despise this woman casting in two mites into the treasury. Plainly the woman was noble who in the divine judgment was found worthy to be preferred to all. Perchance it is she who of her faith has given two testaments for the help of man, and so no one has done more. Nor could any one equal the amount of her gift, who joined faith with mercy. Do you, then, whoever you are, who exercise your life the practice of widowhood, not hesitate to cast into the treasury the two mites, full of faith and grace.
30. Happy is she who out of her treasure brings forth the perfect image of the King. Your treasure is wisdom, your treasure is chastity and righteousness, your treasure is a good understanding, such as was that treasure from which the Magi, when they worshipped the Lord, brought forth gold, frankincense, and myrrh; setting forth by gold the power of a king, venerating God by the frankincense, and by myrrh acknowledging the resurrection of the body. You too have this treasure if you look into yourself: “For we have this treasure in earthen vessels.” You have gold which you can give, for God does not exact of you the precious gift of shining metal, but that gold which at the day of judgment the fire shall be unable to consume. Nor does He require precious gifts, but the good odour of faith, which the altars of your heart send forth and the disposition of a religious mind exhales.
31. From this treasure, then, not only the three gifts of the Magi but also the two mites of the widow are taken, on which the perfect image of the heavenly King shines forth, the brightness of His glory and the image of His substance. Precious, too, are those hardly earned gains of chastity which the widow gives of her labour and daily task, continually night and day working at her task, and by the wakeful labour of her profitable chastity gathering treasure; that she may preserve the couch of her deceased husband unviolated, be able to support her dear children, and to minister to the poor. She is to be preferred to the rich, she it is who shall not fear the judgment of Christ.
32. Strive to equal her, my daughters: “It is good to be zealously affected in a good thing.” “Covet earnestly the best gifts.” The Lord is ever looking upon you, Jesus looks upon you when He goes to the treasury, and you think that of the gain of your good works assistance is to be given to those in need. What is it, then, that you should give your two mites and gain in return the Lord's Body? Go not, then, empty into the sight of the Lord your God, empty of mercy, empty of faith, empty of chastity; for the Lord Jesus is wont to look upon and to commend not the empty, but those who are rich in virtues. Let the maiden see you at work, let her see you ministering to others. For this is the return which you owe to God, that you should make your return to God from the progress of others. No return is more acceptable to God than the offerings of piety.
Source: Concerning Widows (New Advent)