He that showed mercy - His "Jewish" prejudice would not permit him "to name" the Samaritan, but there was no impropriety, even in his view, in saying that the man who showed so much mercy was really the neighbor to the afflicted, and not he who "professed" to be his neighbor, but who would "do nothing" for his welfare.
Go, and do thou likewise - Show the same kindness to "all" - to friend and foe - and "then" you will have evidence that you keep the law, and not "till" then. Of this man we know nothing farther; but from this inimitably beautiful parable we may learn:
1. That the knowledge of the law is useful to make us acquainted with our own sinfulness and need of a Saviour.
2. That it is not he who "professes" most kindness that really loves us most, but he who will most deny himself that he may do us good in times of want.
3. That religion requires us to do good to "all" people, however "accidentally" we may become acquainted with their calamities.
4. That we should do good to our enemies. Real love to them will lead us to deny ourselves, and to sacrifice our own welfare, that we may help them in times of distress and alleviate their wants.
5. That he is really our neighbor who does us the most good - who helps us in our necessities, and especially if he does this when there has been "a controversy or difference" between us and him.
6. We hence see the beauty of religion. Nothing else will induce people to surmount their prejudices, to overcome opposition, and to do good to those who are at enmity with them. True religion teaches us to regard every man as our neighbor; prompts us to do good to all, to forget all national or sectional distinctions, and to aid all those who are in circumstances of poverty and want. If religion were valuable for nothing "but this," it would be the most lovely and desirable principle on earth, and all, especially in their early years, should seek it. Nothing that a young person can gain will be so valuable as the feeling that regards all the world as one great family, and to learn early to do good to all.
7. The difference between the Jew and the Samaritan was a difference in "religion" and "religious opinion;" and from the example of the latter we may learn that, while people differ in "opinions" on subjects of religion, and while they are zealous for what they hold to be the truth, still they should treat each other kindly; that they should aid each other in necessity; and that they should thus show that religion is a principle superior to the love of sect, and that the cord which binds man to man is one that is to be sundered by no difference of opinion, that Christian kindness is to be marred by no forms of worship, and by no bigoted attachment for what we esteem the doctrines of the gospel.

He that showed mercy - Or, so much mercy. His prejudice would not permit him to name the Samaritan, yet his conscience obliged him to acknowledge that he was the only righteous person of the three.
Go, and do thou likewise - Be even to thy enemy in distress as kind, humane, and merciful, as this Samaritan was. As the distress was on the part of a Jew, and the relief was afforded by a Samaritan, the lawyer, to be consistent with the decision he had already given, must feel the force of our Lord's inference, that it was his duty to act to any person, of whatever nation or religion he might be, as this Samaritan had acted toward his countryman. It is very likely that what our Lord relates here was a real matter of fact, and not a parable; otherwise the captious lawyer might have objected that no such case had ever existed, and that any inference drawn from it was only begging the question; but as he was, in all probability, in possession of the fact himself, he was forced to acknowledge the propriety of our Lord's inference and advice.
Those who are determined to find something allegorical, even in the plainest portions of Scripture, affirm that the whole of this relation is to be allegorically considered; and, according to them, the following is the true exposition of the text.
The certain man means Adam - went down, his fall - from Jerusalem, יראה שלום yorih shalom, he shall see peace, perfection, etc., meaning his state of primitive innocence and excellence - to Jericho, (ירחי yareacho, his moon), the transitory and changeable state of existence in this world - thieves, sin and Satan - stripped, took away his righteousness, which was the clothing of the soul - wounded, infected his heart with all evil and hurtful desires, which are the wounds of the spirit - half dead, possessing a living body, carrying about a soul dead in sin.
The priest, the moral law - the Levite, the ceremonial law - passed by, either could not or would not afford any relief, because by the law is the knowledge of sin, not the cure of it. A certain Samaritan, Christ; for so he was called by the Jews, John 8:48 - as he journeyed, meaning his coming from heaven to earth; his being incarnated - came where he was, put himself in man's place, and bore the punishment due to his sins - had compassion, it is through the love and compassion of Christ that the work of redemption was accomplished - went to him, Christ first seeks the sinner, who, through his miserable estate, is incapable of seeking or going to Christ - bound up his wounds, gives him comfortable promises, and draws him by his love - pouring in oil, pardoning mercy - wine, the consolations of the Holy Ghost - set him on his own beast, supported him entirely by his grace and goodness, so that he no longer lives, but Christ lives in him - took him to an inn, his Church, uniting him with his people - took care of him, placed him under the continual notice of his providence and love - when he departed, when he left the world and ascended to the Father - took out two pence, or denarii, the law and the Gospel; the one to convince of sin, the other to show how it is to be removed - gave them to the host, the ministers of the Gospel for the edification of the Church of Christ - take care of him, as they are Gods watchmen and God's stewards, they are to watch over the flock of Christ, and give to each his portion of meat in due season. What thou spendest more, if thou shouldst lose thy health and life in this work - when I come again, to judge the world, I will repay thee, I will reward thee with an eternity of glory.
Several primitive and modern fathers treat the text in this way. What I have given before is, I believe, the meaning of our blessed Lord. What I have given here is generally true in itself, but certainly does not follow from the text. Mr. Baxter's note here is good: "They who make the wounded man Adam, and the good Samaritan Christ, abuse the passage." A practice of this kind cannot be too strongly reprehended. Men may take that advantage of the circumstances of the case to illustrate the above facts and doctrines; but let no man say this is the meaning of the relation; no: but he may say, we may make this use of it. Though I cannot recommend this kind of preaching, yet I know that some simple upright souls have been edified by it. I dare not forbid a man to work by whom God may choose to work a miracle, because he follows not with us. But such a mode of interpretation I can never recommend.

And he said, he that showed mercy to him,.... Meaning the Samaritan; which he was obliged to declare, though of another country and religion, and accounted as an enemy; yet the case was so plain, as put by Christ, that he could not with any honour or conscience, say otherwise:
then said Jesus unto him, go and do thou likewise; such like acts of beneficence and kindness, though to a person of a different nation and religion, and though even an enemy; and by so doing, thou wilt not only appear to be a good neighbour thyself, but to love thy neighbour as thyself.

Go, &c.--O exquisite, matchless teaching! What new fountains of charity has not this opened up in the human spirit--rivers in the wilderness, streams in the desert! What noble Christian institutions have not such words founded, all undreamed of till that wondrous One came to bless this heartless world of ours with His incomparable love--first in words, and then in deeds which have translated His words into flesh and blood, and poured the life of them through that humanity which He made His own! Was this parable, now, designed to magnify the law of love, and to show who fulfils it and who not? And who did this as never man did it, as our Brother Man, "our Neighbor?" The priests and Levites had not strengthened the diseased, nor bound up the broken (Ezekiel 34:4), while He bound up the brokenhearted (Isaiah 61:1), and poured into all wounded spirits the balm of sweetest consolation. All the Fathers saw through the thin veil of this noblest of stories, the Story of love, and never wearied of tracing the analogy (though sometimes fancifully enough) [TRENCH]. Exclaims GREGORY NAZIANZEN (in the fourth century), "He hungered, but He fed thousands; He was weary, but He is the Rest of the weary; He is saluted 'Samaritan' and 'Demoniac,' but He saves him that went down from Jerusalem and fell among thieves," &c.

And he said, He that showed mercy on him - He could not for shame say otherwise, though he thereby condemned himself and overthrew his own false notion of the neighbour to whom our love is due. Go and do thou in like manner - Let us go and do likewise, regarding every man as our neighbour who needs our assistance. Let us renounce that bigotry and party zeal which would contract our hearts into an insensibility for all the human race, but a small number whose sentiments and practices are so much our own, that our love to them is but self love reflected. With an honest openness of mind let us always remember that kindred between man and man, and cultivate that happy instinct whereby, in the original constitution of our nature, God has strongly bound us to each other.