Augustine was the Bishop of Ippona, a coastal area in contemporary Algeria, when he was called to address these accusations and enter the fray. He did this by starting a monumental work made up of twenty-two books whose composition would last fourteen years (from 412 to 426 AD). The internal architecture of the work which in its name De civitate Dei intertwines a Biblical lecture with dialogue with a glorious pagan tradition, reflects this ambitious project: the first part, which is made up of ten books, contains a documented and merciless indictment of the false promises of polytheism, which for St. Augustine was unable to assure success and fortune in the temporal life (I-V) and, even more, blessedness after death (VI-X); the second part of the work, which is made up of ten books, offers in a positive key an alternative history of humanity, which is approached anew as a great fresco in three periods, narrating the origins (XI-XIV), the development (XV-XVIII) and the final outcome (XIX-XXII) of two cities. Understood in a 'mystic' sense, as two alternative communities of life and worship based upon two opposing ways of living love, the city of God and the earthly city differ in their different approaches to the mystery of the creation and redemption: the first welcomes it with humility, the second rejects it and closes itself up in the sinful circle of disastrous self-affirmation.
Book XIX, some pages from which are presented here pages, indeed, that constitute some of the most intense and significant of the whole work opens the third and final section of this second part where the initial argumentation of the doctrine of the supreme good is transformed into a great hymn to peace. Although it is true, in fact, that for a citizen of the civitas Dei the supreme good is eternal life and the supreme evil is eternal death, what matters is the search for the ultimate end which constitutes the inescapable barycentre of the lives of individuals and communities. This tension towards the end is the fundamental fact of the created universe and its name is peace. For Augustine, peace attests to the radical equilibrium of every being in the order of the creation; an equilibrium that in rational creatures becomes a value to be built up freely within the perspective of an ordo amoris. There is, therefore, an original ontological order in which peace announces itself as an 'ordered constitution of parts', as 'tranquillitas ordinis', and an ethical political level that is transformed historically into a task of arduous and incumbent social ordering. A peace as an expression of being is matched by a peace as an expression of love (XIX, 13-14).
From this springs the possibility of a point of tangency between believers and non-believers, all of whom are bound to the building up of an ordered concord in earthly life (XIX, 17). The equality of men before God, in fact, is an expression of an original creatural link that does not authorise any form of potestas naturalis of man over man. Whereas peace expresses the telos of good at every level, both rational and irrational, of the created universe, in the life of relationships it expresses the same telos of good which must actuate itself in the form of an ordinata concordia, organised hierarchically in line with growing levels of complexity (domus, urbs, orbis, mundus).
At this point is opened up the space of a harmonious co-existence between the two cities and peace is the concrete and positive domain of this encounter: compared to the civitas terrena, which to pursue its end on earth at any event needs concord, the civitas Dei peregrina is called to welcome that peace which in the temporal order is only a res, acknowledging its further and liberating value of signum. In other terms, in temporal peace the civitas Dei peregrina must be faithful to the signum by respecting the res (it takes on, that is to say, temporal peace as a prior experience of eternal peace), whereas the civitas terrena can be faithful to the res by respecting the signum and avoiding having the fragile earthly order as an absolute end. Indeed, the civitas Dei peregrina, tends, in virtue of grace, to pax aeterna, but it lives, in virtue of nature, in pax terrena. Temporal peace thus becomes an expression of a relative order and value, the point of arrival in the natural minimal aspiration of Babylonia and at the same time the point of departure of that highest unifying tension in which one can announce and prefigure the peace of Jerusalem.
In the nineteenth book of De civitate Dei the doctrine of the supreme good is transformed into a great hymn to peace which is seen as the fundamental fact of the creation, which aims at its achievement. At an ontological level it presents itself as an 'ordered constitution
of parts', whereas at an ethical-political level it invokes a task of arduous construction.