If you know one parable Jesus taught, chances are you know this one. Challenged by a lawyer who was trying to prove that obtaining eternal life wasn't a straightforward business, Jesus tells him, Obey the law and you will live. Love God, love your neighbour, that'll do.
Can you define "neighbour" for me?
Yes I can. Listen to this story. A man is mugged, and two people have an opportunity to help him. Both are his brothers, fellow Jews, and not just any old Jews, but members of the religious tribe, a Levite and a priest.
These are people who should know the law.
Well perhaps they do. The law says if you touch a dead body you will be defiled all day. For the rest of that day you will be unable to perform your religious duties. Surely obedience to God's law means keeping yourself clean, keeping yourself available to serve God's people as his representatives in the Temple.
This is a little like the "don't heal on the sabbath" argument that Jesus has had already. If the sabbath is meant to be a day of life and hope, a day of worship and freedom, then how come it's become a day of prohibitions? Jesus clearly thinks that the sabbath has become self-serving, not people-serving.
And so in Jesus' story, it's someone who is not yoked to the law who is free to truly obey it. A Samaritan comes by, not troubled by thoughts of ritual uncleanness, and shows mercy and kindness to the man in need.
What did Jesus quote to the pharisees once? "I desire mercy, not sacrifice." (This comes in Matthew's version of the account of the calling of the tax collector).