As people are already aware, I am being named auxiliary bishop of Montreal. This means I am not the head bishop of that diocese, but that I will assist him in his duties as bishop.
What is less known, however, is that even auxiliary bishops have a diocese. Mine is not in Canada, but in Italy: it is the diocese of Treba. Yes, people actually live there (today it is known as Trevi nel Lazio, in the province of Frosinone). However, I will not have any jurisdiction over them: I am what is called a titular bishop, not a diocesan bishop.
You may be wondering where these sorts of fictional dioceses come from. In every case the titular diocese was once a regular diocese with its own diocesan bishop. However, in most cases some war or other calamity either required the bishop to flee, or required the pastoral care of those people pass to someone else. As well, because travelling was often difficult some parts of the world had a great many small dioceses, which eventually got merged. One of these scenarios likely happened to my diocese at some point. Now that the jurisdiction of this territory has passed to another local Italian diocesan bishop, the title can be used to appoint an auxiliary bishop elsewhere in the world.
Such as myself, in Montreal.
I should point out that not everyone believes in the use of titles like this for auxiliary bishops — after all, could we not just appoint priests as auxiliary bishops without this sort of legal fiction? I do think that there is perhaps room for development in theology and canon law in this area, especially as we continue to explore the concept of a “local Church” in our ecumenical dialogue with the Orthodox.
All this being said, though, while I have no living members of the diocese to take care of, I do plan on saying mass on November 2 (the feast of All Souls) for the deceased members of that local Church. The Treba diocese did exist for 500+ years (longer than Canada!) and who knows? Maybe there is still a soul or two waiting for someone to pray for them and help them out of purgatory. Who better to offer that prayer than the bishop of that historical place?
I certainly plan on visiting the town of Trevi nel Lazio the next time I am in Italy, and I’d be thrilled to learn more about the history of the place. If anyone can help out with info, please drop me a line.
UPDATE (August 5): This text was sent to me by a historian of the episcopate:
Ancien évêché (Treba Augusta) attesté dès les Ve-VIe siècles, situé dans la province de Rome (Latium, sur le site de la moderne Trevi del Lazio), près des sources de l’Anio (affluent du Tibre), dans les monts Simbruini, à quelque 28 km NNO de Frosinone; il fut supprimé au milieu du XIe siècle (par Victor II ou Nicolas II, selon les sources), et réuni au diocèse d’Anagni et ultérieurement au territoire de l’abbaye de Subiaco. Apparaît pour la première fois dans l’AP 1971. À ne pas confondre avec Trevi, province de Pérouse en Ombrie, à quelque 15 km au nord de Spolète et 9 km SSE de Foligno, autre ancien évêché (datant de la fin du IIIe siècle), lui aussi maintenant disparu. (Moroni, G. Dizionario di erudizione storico-ecclesiastica, v. 80, 47-49)