Pope Benedict XVI, since his election to the papacy, has urged Catholic clergy and theologians to interpret the documents of the second Vatican Council using a "hermeneutic of continuity." This thesis seeks to answer whether such a hermeneutic is possible by focusing on one aspect of the Dogmatic Constitution on the Church, Lumen Gentium. The methodology here employed is a critical analysis of one of the major patristic sources of Lumen Gentiums teaching, St. Augustine of Hippo. In claiming St. Augustines support for its doctrine, Lumen Gentium also offers an interpretation of his thought. For Lumen Gentiums teaching to be plausible, we must be able to conclude that Augustines teaching is essentially identical to it. In that connection, Lumen Gentiums claim that the Church is both a spiritual and visible reality forces us to consider a controverted topic in Augustinian studies: can Augustines city of God be identified with the hierarchical Church? In order to resolve that question, we will examine both the historical and eschatological aspects of the Church in Augustines thought, with some reference (treated in an appendix) to the compatibility between his theory of predestination and his ecclesiology. Further, what the Council meant when it said that the Church of Christ subsists in the Catholic Church, and whether this change in terminology, along with its implications in the field of ecumenism, can be reconciled with St. Augustines ecclesiology must be determined with a view to establishing the continuity between pre and post conciliar Catholic ecclesiology. St. Augustine developed his understanding of the nature of the Church in the early years of his ecclesiastical career through his polemical battles with the Donatist schismatics, and so the history of that schism is related in an appendix.

Pope Benedict XVI, since his election to the papacy, has urged Catholic clergy and theologians to interpret the documents of the second Vatican Council using a "hermeneutic of continuity." This thesis seeks to answer whether such a hermeneutic is possible by focusing on one aspect of the Dogmatic Constitution on the Church, Lumen Gentium. The methodology here employed is a critical analysis of one of the major patristic sources of Lumen Gentiums teaching, St. Augustine of Hippo. In claiming St. Augustines support for its doctrine, Lumen Gentium also offers an interpretation of his thought. For Lumen Gentiums teaching to be plausible, we must be able to conclude that Augustines teaching is essentially identical to it. In that connection, Lumen Gentiums claim that the Church is both a spiritual and visible reality forces us to consider a controverted topic in Augustinian studies: can Augustines city of God be identified with the hierarchical Church? In order to resolve that question, we will examine both the historical and eschatological aspects of the Church in Augustines thought, with some reference (treated in an appendix) to the compatibility between his theory of predestination and his ecclesiology. Further, what the Council meant when it said that the Church of Christ subsists in the Catholic Church, and whether this change in terminology, along with its implications in the field of ecumenism, can be reconciled with St. Augustines ecclesiology must be determined with a view to establishing the continuity between pre and post conciliar Catholic ecclesiology. St. Augustine developed his understanding of the nature of the Church in the early years of his ecclesiastical career through his polemical battles with the Donatist schismatics, and so the history of that schism is related in an appendix.

Ce travail est une réflexion théologique sur la notion canonique de suppléance. La suppléance est restreinte au pouvoir exécutif de gouvernement (canon 144). D’où une étude sur le lien entre suppléance et potestas sacra et les conditions d’une application aux laïcs. Des cas sont recensés dans lesquels le salut d'une âme est engagé. Leur analyse théologique établit une ecclésiologie de l'exception à partir de l’adage : necessitas non habet legem, de l'appartenance à l’Église et du statut des divers groupes ecclésiaux. Le subsistit in et la notion de communion en sont éclairées. L’ecclésiologie de l'exception est le domaine propre de la suppléance qui intervient aussi dans l'Institution par le sensus fidei et les charismes. D’où une réévaluation de : « hors de l’Église, point de salut ». La suppléance est un critère herméneutique utilisable en exégèse (Galates : place de Paul) et en histoire (Tertullien, Cyprien : absence de potestas sacra comme limite irréductible à l'exercice supplétoire). / This work is a theological reflection on supplying canonical notion. Supplying is restricted to executive power of governance (can. 144). Hence we study the link between supplying process and "potestas sacra" and the application requirements to laypersons. We make an inventory of some cases in which the salvation of souls is bound. Their theological analysis establishes an ecclesiology of the exception from the saying : necessitas non habet legem, the membership of Church and the status of some ecclesial communities. The subsistit in and the notion of communion are clarifying. The ecclesiology of the exception is the proper field of supplying process which also occurs into the Institution through sensus fidei and charismas. Hence a reappraisal of the adage : « no salvation outside the Church ». Supplying process is an hermeneutical criterion useful to exegesis (Galatians : Paul’s place) and history (Tertullian, Cyprian : lack of potestas sacra as irreducible limit of suppletory exercise).