On the words of the Gospel, Luke x.38, "And a certain woman named Martha received him into her house," etc.
1. The words of our Lord Jesus Christ which have just been read out of the Gospel, give us to understand, that there is some one thing for which we must be making, when we toil amid the manifold engagements of this life. Now we make for this as being yet in pilgrimage, and not in our abiding place; as yet in the way, not yet in our country; as yet in longing, not yet in enjoyment. Yet let us make for it, and that without sloth and without intermission, that we may some time be able to reach it.
2. Martha and Mary were two sisters, true kinswomen both, not only in blood, but in religion also; both clave to the Lord, both with one heart served the Lord when He was present in the flesh. Martha received Him, as strangers are usually received. Yet it was the handmaid received her Lord, the sick her Saviour, the creature her Creator. And she received Him to be fed in the body, herself to be fed in spirit. For the Lord was pleased to "take on Him the form of a servant,"  and "having taken the form of a servant" in it to be fed by servants, by reason of His condescension, not His condition. For this truly was condescension, to allow Himself to be fed by others. He had a body, wherein He might hunger indeed and thirst; but do ye not know that when He hungered in the wilderness Angels ministered to Him?  So then, in that He was pleased to be fed, He showed favour to them that fed Him. And what marvel is this, seeing He showed this same favour to the widow as touching the Holy Elias, whom He had before fed by the ministry of a raven?  Did He fail in His power of feeding him, when He sent him to the widow? By no means. He did not fail in His power of feeding him, when He sent him to the widow; but He designed to bless the religious widow, by means of her pious office paid to His servant. Thus then was the Lord received as a guest, "who came unto His own, and His own received Him not: but as many as received Him, to them gave He power to become the sons of God:"  adopting servants, and making them brethren; redeeming captives, and making them co-heirs. Yet let none of you, as perhaps may be the case, say, "O blessed they who obtained the grace  to receive Christ into their own house!" Do not grieve, do not murmur, that thou wert born in times when thou seest the Lord no more in the flesh; He has not taken this blessedness from thee. "Forasmuch," says He, "as ye have done it unto the least of Mine, ye have done unto Me." 
3. These few words, as the shortness of the time allowed me, would I speak concerning the Lord who was pleased to be fed in the flesh, while He feedeth in the spirit: let us now come to the subject which I have proposed concerning unity. Martha, who was arranging and preparing to feed the Lord, was occupied about much serving. Mary her sister chose rather to be fed by the Lord. She in a manner deserted her sister who was toiling about much serving, and she sat herself at the Lord's feet, and in stillness heard His word. Her most faithful ear had heard already; "Be still, and see that I am the Lord."  Martha was troubled, Mary was feasting; the one was arranging many things, the other had her eyes upon the One. Both occupations were good; but yet as to which was the better, what shall we say? We have One whom we may ask, let us give ear together. Which was the better, we heard now when the lesson was read, and let us hear again as I repeat it. Martha appeals to her Guest, lays the request of her pious complaints before the Judge, that her sister had deserted her, and neglected to assist her when she was so busied in her serving. Without any answer from Mary, yet in her presence, the Lord gives judgment. Mary preferred as in repose to commit her cause to the Judge, and had no mind to busy herself in making answer. For if she were to be getting ready words to answer, she must remit her earnest attention to hear. Therefore the Lord answered, who was in no difficulty for words, in that He was the Word. What then did He say? "Martha, Martha."  The repetition of the name is a token of love, or perhaps of exciting attention; she is named twice, that she might give the more attentive heed. "Martha, Martha," hear: "Thou art occupied about many things: but one thing is needful;"  for so meaneth unum opus est, not "one work," that is, one single work, but one is needful, is expedient, is necessary, which one thing Mary had chosen. 
4. Consider, Brethren, this "one thing," and see if even in multitude itself anything pleases, but "this oneness." See how great a number, through God's mercy, ye are: who could bear you, if ye did not mind "one thing"? Whence in this many is this quiet? Give oneness, and it is a people; take oneness away, and it is a crowd. For what is a crowd, but a disordered multitude? But give ear to the Apostle: "Now I beseech you, brethren." He was speaking to a multitude; but he wished to make them all "one." "Now I beseech you, brethren, that ye all speak the same thing, and that there be no schisms among you; but that ye be perfected in the same mind, and in the same knowledge."  And in another place, "That ye be of one mind, thinking one thing, doing nothing through strife or vainglory."  And the Lord prays to the Father touching them that are His: "that they may be one even as We are One."  And in the Acts of the Apostles; "And the multitude of them that believed were of one soul, and of one heart."  Therefore, "Magnify the Lord with me, and let us exalt His Name in one together."  For one thing is necessary, that celestial  Oneness, the Oneness in which the Father, and the Son, and Holy Spirit are One. See how the praise of Unity is commended to us. Undoubtedly our God is Trinity. The Father is not the Son the Son is not the Father, the Holy Spirit is neither the Father, nor the Son, but the Spirit of both; and yet these Three are not Three Gods, nor Three Almighties; but One God, Almighty, the whole Trinity is one God; because One thing is necessary. To this one thing nothing brings us, except being many we have one heart.
5. Good are ministrations done to the poor, and especially the due services and the religious offices done to the saints of God. For they are a payment, not a gift, as the Apostle says, "If we have sown unto you spiritual things, is it a great thing if we shall reap your carnal things?"  Good are they, we exhort you to them, yea by the word of the Lord we build you up, "be not slow to entertain" the saints. Sometimes, they who were not aware of it, by entertaining those whom they knew not, have entertained angels.  These things are good; yet better is that thing which Mary hath chosen. For the one thing hath manifold trouble from necessity; the other hath sweetness from charity. A man wishes when he is serving, to meet with something; and sometimes he is not able: that which is lacking is sought for, that which is at hand is got ready; and the mind is distracted. For if Martha had been sufficient for these things, she would not have demanded her sister's help. These things are manifold, are diverse, because they are carnal, because they are temporal; good though they be, they are transitory. But what said theLord to Martha? "Mary hath chosen that better part." Not thou a bad, but she a better. Hear, how better; "which shall not be taken away from her."  Some time or other, the burden of these necessary duties shall be taken from thee: the sweetness of truth is everlasting. "That which she hath chosen shall not be taken away from her." It is not taken away, but yet it is increased. In this life, that is, is it increased, in the other life it will be perfected, never shall it be "taken away."
6. Yea, Martha, blessed in thy good serving, even thou (with thy leave would I say it) seekest this reward for all thy labour -- quiet. Now thou art occupied about much serving, thou hast pleasure in feeding bodies which are mortal, though they be the bodies of Saints; but when thou shalt have got to that country, wilt thou find there any stranger whom thou mayest receive into thine house? wilt thou find the hungry, to whom thou mayest break thy bread? or the thirsty, to whom thou mayest hold out thy cup? the sick whom thou mayest visit? the litigious, whom thou mayest set at one? the dead, whom thou mayest bury? None of all these will be there, but what will be there? What Mary hath chosen; there shall we be fed, and shall not feed others. Therefore there will that be in fulness and perfection which Mary hath chosen here; from that rich table, from the word of the Lord did she gather up some crumbs. For would ye know what will be there? The Lord Himself saith of His servants: "Verily I say unto you, that He will make them to sit down to meat, and will pass by  and serve them."  What is "to sit down to meat," but to "be still"? What is, "to sit down to meat," but to rest? What is, "He will pass by and serve them"? First, He passeth by, and so serveth. And where? In that heavenly Banquet, of which he saith, "Verily I say unto you, Many shall come from the East and West, and shall sit down with Abraham, and Isaac, and Jacob, in the kingdom of heaven."  There will the Lord feed us, but first He passeth on from hence. For (as ye should know) the Pasch is by interpretation Passing-over. The Lord came, He did divine things, He suffered human things. Is He still spit upon? Is He still struck with the palm of the hand? Is He still crowned with thorns? Is He still scourged? Is He still crucified? Is He still wounded with a spear? "He hath passed by." And so too the Gospel tells us, when He kept the Paschal feast with His disciples. What says the Gospel? "But when the hour was come that Jesus should pass out of this world unto the Father."  Therefore did He pass,  that He might feed us; let us follow, that we may be fed.
 Philippians 2:7.  Matthew 4:11.  1 Kings 17:6.  John 1:11, 12.  Meruerunt.  Matthew 25:40.  Psalm 46:10.  Luke 10:41.  Luke 10:42.  St. Augustin is explaining the words unum opus est, which in themselves might mean, "there is one work," or as in the text.  1 Corinthians 1:10.  Philippians 2:2, 3.  John 17:22.  Acts 4:32.  Psalm 34:3.  Supernum.  1 Corinthians 9:11.  Hebrews 13:2.  Luke 10:42.  parelthon; transiens, Vulgate.  Luke 12:37.  Matthew 8:11.  John 13:1.  metabe; transeat, Vulgate.
 Matthew 4:11.
 1 Kings 17:6.
 John 1:11, 12.
 Matthew 25:40.
 Psalm 46:10.
 Luke 10:41.
 Luke 10:42.
 St. Augustin is explaining the words unum opus est, which in themselves might mean, "there is one work," or as in the text.
 1 Corinthians 1:10.
 Philippians 2:2, 3.
 John 17:22.
 Acts 4:32.
 Psalm 34:3.
 1 Corinthians 9:11.
 Hebrews 13:2.
 Luke 10:42.
 parelthon; transiens, Vulgate.
 Luke 12:37.
 Matthew 8:11.
 John 13:1.
 metabe; transeat, Vulgate.