St. Thomas Aquinas, the leader of Scholastic thinkers, gives us a very clear and helpful analysis of the problem of city life:
Now since men must live in a group because they are not sufficient unto themselves to procure the necessities of life were they to remain solitary, it follows that a society will be more perfect the more it is sufficient unto itself to procure the necessities of life (Bk. I, c. i). For an individual to lead a good life two things are required. The first and most important is to act in a virtuous manner, for virtue is that by which one lives well; the second, which is secondary and as it were instrumental, is a sufficiency of those bodily goods whose use is necessary for an act of virtue (Bk. I, c. 15).
Now there are two ways in which an abundance of foodstuffs can be supplied to a city. The first is where the soil is so fertile that it nobly provides for all the necessities of human life. The second is by trade, through which the necessities of life are brought to the town from different places. But it is quite clear that the first means is better. For the higher a thing is the more self-sufficient it is; since whatever needs another's help is by that very fact proven inferior. But that city is more fully self-sufficient which the surrounding country supplies with all its vital needs, than is another which must obtain these supplies by trade. A city which has an abundance of food from its own territory is more dignified than one which is provisioned by merchants. It is safer, too, for the importing of supplies can easily be prevented