Jesus' life and ministry, at least in the Gospels of Matthew, Mark and Luke, are almost entirely set in Galilee, and in these Gospels, after having started his ministry, Jesus goes to Jerusalem once and once only. That is his destiny. That this is an entirely different presentation from that of John is not our concern here and now, and which is 'true' in the crudest sense of that term is irrelevant here - we are concerned primarily with how Luke saw it.
There seems to be, in Luke's presentation of the Good News, more of an emphasis on Jerusalem than there is in Matthew and Mark. The ministry is presented as starting with the retreat into the wilderness, where Matthew and Luke run almost parallel. It is, however, only Luke who mentions Jerusalem by name at that point -- Matthew says 'the holy city'.
At another great turning point in the story line, namely, the Transfiguration, it is Luke alone who mentions Jerusalem, as being where Jesus' life-work is to be accomplished. This is what Moses and Elijah are talking about -- in Mark and Matthew, they are simply talking, no more -- so in some sense Matthew and Mark are simply recounting something which 'happened', whilst Luke is interpreting it.
In today's reading, which follows shortly on the Transfiguration, we hear that Jesus 'set his face to go up to Jerusalem'. In between we hear how he tried to make his disciples understand that he is going to Jerusalem not as a triumphant Messiah wielding 'power and might', but to be 'delivered into the hands of men' and thus to suffer. But the disciples were too busy quarrelling with one another as to who was the most important to listen to him.
Throughout the third Gospel there is this emphasis on Jerusalem -- showing, I think, how Jesus was related to the centre of Jewish history and worship. He is presented in the temple as a child; we have the wonderful stories of Simeon and Anna who, we are told, was 'waiting for the redemption of Jerusalem'. And there to drive the message home, a few years later Jesus gets lost, remaining behind in Jerusalem where he is in due course found -- and where else than where you would expect him, 'in my father's house'?
To what extent Luke makes use here of midrash -- a traditional Jewish method of seeking to discover within a story a greater depth of meaning than that which lies on the surface -- one cannot say definitively, but there can be few scholars nowadays who doubt that the Lucan infancy narratives use this form.
How much, one may then ask, is this actually carried over into the rest of the Gospel, and, of course in Luke's case, into the Acts of the Apostles? We should, I think, consider how Luke's account of the Last Supper may or may not fit into this pattern. And then there is the wonderful account of the journey to Emmaus, ending with the eucharist presented in terms of a resurrection appearance. Midrash?
What about Luke's account of the Ascension? -- clearly a staged piece with deeper meaning and significance rather than an account of something which simply 'happened'. Note that if anything like this occurs at all in Matthew or Mark it is in Galilee where Jesus makes his final speech to his disciples. In Luke's account the scene ends with their returning to Jerusalem -- a Sabbath day's journey away -- and here they wait for the gift of the Spirit at Pentecost -- these all fit together so neatly!
Now, however, in Luke's oeuvre the emphasis changes radically. Jerusalem remains the focal point from which God's revelation emanates, but the whole direction is given by Paul's missionary movement working and spreading towards the capital of the world. When Paul reaches Rome Luke loses interest in him. He is not concerned with what follows: the story of Paul's subsequent life.
The 'Light which is to lighten the gentiles and be the glory of Israel' -- there right at the beginning of Luke's work -- has spread to the secular world. Has it transformed the 'worldly empire' or been eclipsed by it? There lies the enigma.
But at its heart is Jerusalem, to which Jesus turned his steps. It remains -- as it always will if the whole story is to mean anything -- the focal point.