One of my guilty pleasures has long since been the study of maps – both the aesthetic of beautifully made maps, as the subjects they depict. The course of boundaries of countries and provinces and especially the reason why these are where they are. The resources to entertain this pleasure are plentiful: atlases and online maps are readily available everywhere. But as a Catholic there is a field which is a bit harder to study: the maps of dioceses.
Since the early centuries of Christianity the Church has felt the need to organise itself geographically. The faithful of specific areas fell under the legal jurisdiction of one bishop, who was also their chief shepherd, the successor to the apostles, although he would often delegate duties to his priests. After all, a bishop can’t be everywhere at the same time.
In many ways, that is still the situation: the worldwide Church is divided into Church provinces, which are divided into dioceses, which, finally, are divided into parishes. Church provinces often coincide with (parts of) countries, but dioceses can have interesting and seemingly random boundaries. Often, especially in Europe, they are the remains of historical borders of countries and peoples.
Sadly, it is pretty hard to come by maps that show the boundaries of dioceses. Some websites of bishops’ conferences show them, especially in western countries, but they are few and far between. So, for anyone interested in finding out what part of a country falls under which diocese, there is often much puzzling to be done.
Luckily, not so for the dioceses of the Netherlands. The map to the left comes from the website of the Dutch Church province, and it shows that most of the boundaries of the seven dioceses coincide with those of the twelve provinces of the Netherlands. But there is only one diocese, Roermond, which covers completely the same ground as a province: Limburg. All other dioceses show deviations from the better-known boundaries of the provinces.
In the north, the Diocese of Groningen-Leeuwarden covers three provinces: Groningen, Drenthe and Friesland, and part of a fourth: the Noordoostpolder is part of Flevoland. Also, the southern border of the diocese does not coincide with the southern border of Drenthe. When the diocese was established in 1955, some parishes in Drenthe were excluded, while others in the province of Overijssel were included.
The Archdiocese of Utrecht consists of the province of Utrecht, the middle part of the province of Flevoland, almost all of Overijssel (except for those few parishes mentioned above), and most of Gelderland (except for the part south of the River Rhine). Earlier those month, the archdiocese also lost two parishes, one to Haarlem-Amsterdam and the other to Rotterdam.
The Diocese of Haarlem-Amsterdam consist of the province of Noord-Holland and the south-western part of Flevoland (the only province divided over three dioceses), and one parish in the province of Utrecht (as mentioned above).
The Diocese of Rotterdam almost totally coincides with the province of Zuid-Holland, except for the aforementioned parish in Utrecht.
The Catholic south of the Netherlands is neatly spread over three dioceses: Breda consist of the province of Zeeland and the western half of Noord-Brabant; ‘s-Hertogenbosch has the eastern half of Noord-Brabant as well as the bit of Gelderland beneath the Rhine; Roermond has been mentioned above: it consists of the province of Limburg.
The Dutch situation is mostly a practical one, with the basis found in the number of Catholics present in an area, as well as the social cohesion between cities and areas. Parishes have been transferred from one diocese to another based on their relations with neighbouring parishes and communities.
In other countries, for example in Germany, the boundaries of dioceses are based on situations from the past. German dioceses are often based on the long-gone principalities of the German Empire and the Weimar Republic, which makes for strange but interesting situations where dioceses consist of two or more distinct parts.
Sometimes speeches or homilies are simply good; somehow they work, their separate parts come together to form one whole that manges to reach its audience. Let that be the very subject that Bishop Rob Mutsaerts spoke about in his 
Bishop Thomas J. Tobin of Providence, United States, writes 
Press release following the publication of the report by the Deetman Commission
In Caelo et in Terra 