The economic pressure on Jews to move from the farm to the city was basic to Levitical law. The closer a man lived to Israel's holy city, the less time he had to spend on the road. If he had to spend time on the road, he might as well become a traveling salesman. The Israelites were pressured economically by the laws of the festivals and the sacrifices to become a nation of traders. The economic laws of Leviticus also pressured the farmers of Israel to move into the cities. The residents of cities were in turn pressured to become international traders. This does not mean that there were to be no Israelite farmers in Israel, but there can be no doubt that the general thrust of the economic incentives under the Mosaic law's system of costs and benefits was to move God's covenant people off the farms and into the cities. They were to become a nation of manufacturers, shopkeepers, traders, and bankers -- an early version of what England became in the nineteenth century.
His argument revolves around the three required festivals of ancient Israel (Passover, Pentecost, Tabernacles) and the mandatory journeys required for them during the peak agricultural season. He states that even though he believes the Torah pushes Israel in this direction, that it was never carried out, because (mainly) of sin. He goes on to say that the logical thing for an Israelite farmer far from Jerusalem to do would be to lease his land to Gentiles, since they didn't need to go to the feast. The Israelite and his family would move close to Jerusalem and the agricultural areas would be under the control of those who do not know God and did not care about his creation (North brings up his claim that being agrarian is always tied to paganism--based on the root of the word--hence the modern environmental movement; I think here we have the classic rhetoric North is known for, tossing baby and bathwater down the drain).
While creative, I don't think that this thesis works, but I think it should get Christians thinking about our place in God's world and our place in relationship to those who are not followers of the one true God. I don't think that Israelites would have become absentee landlords, living close to the city, and leaving all their food needs in the hands of Gentiles. Your spiritual enemies having control of your food supply is just as dangerous as your political enemies holding the same power. Controlling one's property from afar is fraught with problems: what would stop a Gentile, who enjoyed his rashers of bacon, from bringing a few swine onto holy land? Not the owner, that's for sure. He's out in the city. Plus, if the land stewardship of the Gentile is poor, it will take a long time to rectify it, if the now practically landless Israelite even cares anymore (his money is coming from his city endeavors, after all). Absenteeism doesn't work economically.
Instead, I think going back to Genesis, the original agricultural book, gives us hints on what situation the Mosaic economy would actually present. Adam, the gardener, was told to tend to the garden and also subdue the beasts, including the beasts of burden. He was, in effect, a manager. The image of beasts, over which Adam is to be ruler, comes up various times in Scripture, eventually being changed to a metaphor of Israel (Adam) and the Gentiles (Beasts) in Daniel 7. Abraham, the father of the faithful who Paul (among others) enjoins us to imitate, does not retire to the city like Lot, but rather manages and directs the affairs of his 300+ non-Abrahamic servants. Going to the city, in fact, is seen as an act of rebellion. These two men, Adam and Abraham, give the model of what the Mosaic law was trying to accomplish: Israelites were to bring Gentiles under their authority by putting them to work, showing them the benefits of the covenant, and training them how to live and work righteously. From there evangelism would spread throughout the globe, taking wise agriculture and wise living along with it. Traveling merchants can only do so much; they are placeless and do not have time for discipleship.
If we transfer this forward, we can start to see how the Christian is to carry this out. The Israelites had inherited the land of Canaan; we have inherited the world. We are supposed to be doing what we do well enough so that we can rise to positions of authority, whether owner or manager or whatever, so that the Gentiles (non-believers) under our care might share in the blessings of a covenantally faithful individual. We train them, manage them, and share our faith-in-action by our work. Christians are supposed to be managers.
This places things in the proper authority structure: God - Jesus - members of the Church - those outside the Church - the non-human world. As North goes on to say later in the book, this relationship is judicial: each one is responsible for each link below themselves on the chain (I should not that this obviously is not an ontological chain). That should inspire quite a bit of humility into Christians: when we mess up, the effects are judicially placed on both our fellow human beings and the non-human creation. We are responsible for the protection and flourishing of them. If we fail, or act evilly towards them, then we feel the consequences and so do they. This, of course, raises the question of how we are to act towards them. Maybe starting with Jesus' reinterpretation of the Mosaic code in Matthew 5-7 is a good start; there is no place for a heavy-handed, coercive, violent relationship towards our fellow human beings, whether they believe in our God or not, or towards the non-human creation. A good manager doesn't demean his charges, but helps them to flourish at work and as human beings.
This also has implications for the Church as a whole and its relationship to the other structures of this world. More on this anon.