The passage
      v34. Mark has the teacher of the law asking a genuine question, while Matthew paints the question as a further attempt to trip Jesus up. The Sadducees might be debated out, but the Pharisees still have a way to go.
      v35-36. One of their number, an "expert in the law" (a scribe, or teacher of the law and member of the Pharisee party) sets out to trip Jesus up with a question that was obviously hotly debated in their own circles. It's possible they had been unable resolve the question themselves and so thought they could show Jesus up. Rabbi Hillel (AD20), when challenged by a Gentile to summarize the law in the short time he could stand on one leg, said "what is hateful to you, do not do to anyone else. This is the whole law; all the rest is commentary. Go and learn it." In fact, experts of the law at the time were not sure that was right to grade the law. Some even argued that all the commandments were of equal value. So, obviously the Pharisees were quite taken with their "tricky" question.
      v37-39. Jesus quotes Deuteronomy 6:5, describing it as the "first and greatest", meaning primary - in order of importance it is first. A person is to love God with their whole being. "Heart... soul.... mind" are not exclusive parts of the human nature. Every faculty and capacity is to love God. For the second commandment, the next in order, Jesus quotes Leviticus 19:18. This command also calls for love, but this time toward the "neighbor". In Leviticus, the neighbor is a fellow Israelite or a resident alien. Jesus clearly extends the demand of love in the parable of the Good Samaritan in such a way as to make love an ideal of perfection which transcends race or creed.
      v40. In what sense does the Law and the Prophets "hang" on these two commandments? All the commandments found in the scriptures, both small and great, hang from the command to love, of which, love of God is the foremost. So, the two great commandments serve as a summary of our duty toward God and neighbor. All other commands derive from these two commands. Jesus does not claim that this is an original combination, but it obviously silences the "expert in the law".

The ethics of love
      Ethical principles enable human society to survive with some sense of order. There was a time when Western society affirmed a Biblical agenda, particularly the two great commandments and their more extended derivation in the ten commandments. In recent years, Biblical ethics have been sidelined in the quest for a new ethical agenda.
      In the West, hedonism is a popular ethical principle. "I just want to be happy", "happiness is the meaning of life". We all want to be happy, but as an ethical principle it does have limitations. My happiness may result in another's sadness. I may like loud music, but the rest of the family may not. We could argue for the happiness of the greatest number, but then if we are the odd person out, the happiness of others may be our curse.
      In many Western societies the social justice agenda of the left has begun to dominated the political debate, although today we find an increasing number of voices raised against the "isms" of our day - multiculturalism, feminism...... In the same way as socialism has collapsed as a viable political structure, so it is beginning to founder as a viable social structure.
      In the new age of economic rationalism, all we are left with is the rather shallow ethic of pragmatism. The ethics of an issue then comes down to "does it work?" Racist vilification is then deemed wrong, not because it is unloving, makes people unhappy or in particular, undermines muliculturalism, but because it can affect social cohesion and therefore, economic stability.
      Jesus summarized the whole law in the two great commands. They are commands that stand together, demanding each other. We can't love God without loving our neighbor; we can't love our neighbor unless we love God. In the end, all Biblical law derives from the command to love and serves to give practical expression to love. In that sense, the law is not just a practical manual for life, for without devotion and heart it is sterile and useless. So then, the law is summed up in love, a love that expresses ultimate care toward the other's best interest.
      Ultimately, the two great commands transcend, even abolish the formal keeping of Biblical laws. For the believer in Christ, the ideal of love, in union with the indwelling Spirit, compels us to "do by nature things required by the law", demonstrating that the law is written on our hearts, Rom.2:12-16.

v35
      nomikoV (oV) "an expert in the law" - a scribe who is learned in the law of Moses, lawyer. The word is missing in some manuscripts. "An expounder of the Law", Weymouth.
      peirazwn (peirazw) pres. part. "tested" - test, try, trip up, tempt. The participle is probably adverbial of purpose, "put a question in order to tempt (test) him", Moffatt. Probably in the sense of "entrap", "tried to catch him out with this question", REB.

v36
      didaskale (oV) voc. "teacher" - rabbi. A general respectful address.
      poia interrogative pro. "which" - Quantitative "how much?" Possibly qualitative, "what sort of commandment is great?", Wallace.
      megalh "greatest" - great. Although positive, usually translated as a superlative. Mark has "first in importance", which means the same. Jesus is probably being baited into a discussion over the relative importance of the 613 biblical laws, and this for the purpose of catching him out and damaging his credibility. "Master, which commandment of those contained in the law is the greatest", Cassirer.

v37
      agaphseiV (agapaw) fut. "love" - you shall love. A future indicative used as a command (imperatival future) - common in quotes from the Old Testament.
      en oJlh/ "with all" - in all. The threefold statement means "love God wholeheartedly." Ref. Deut.6:5. "Love the Lord your God with all your passion, prayer and intellegence", Peterson.

v38
      hJ megalh pos. adj. "greatest" - great. Again the positive is used for an intended superlative, cf. v36.
      prwth adj. "first" - former, paramount. "First in importance."

v39
      oJmoia auth/ "[is] like it" - "Resembles it", JB.
      ton plhsion adv. "neighbor" - near, neighboring. As a substantive, as here, "one who is part of a particular group." For a Jew, one's neighbor is their fellow Jew. Apart from the parable of the Good Samaritan, does Jesus actually widen his understanding of the group to the whole human race, or does he stay with the popular understanding of love as a quality of care directed toward one's brother, cf. 1Jn.4:20?
      wJV seauton "as yourself" - "As much as you love yourself", TH.