hief house of God, the cathedral church was the _Domus Dei_, and
from this name the German _Domkirche_, or _Dom_, is derived, as also the
Swedish _Domkyrka_, and the Italian _Duomo_.

_History and Organization._--It was early decreed that the _cathedra_ of
a bishop was not to be placed in the church of a village, but only in
that of a city. There was no difficulty as to this on the continent of
Europe, where towns were numerous, and where the cities were the natural
centres from which Christianity was diffused among the people who
inhabited the surrounding districts. In the British islands, however,
the case was different; towns were few, and owing to other causes,
instead of exercising jurisdiction over definite areas or districts,
many of the bishops were bishops of tribes or peoples, as the bishops of
the south Saxons, the west Saxons, the Somersaetas and others. The
_cathedra_ of such a bishop was often migratory, and was at times placed
in one church, and then another, and sometimes in the church of a
village. In 1075 a council was held in London, under the presidency of
Archbishop Lanfranc, which, reciting the decrees of the council of
Sardica held in 347 and that of Laodicea held in 360 on this matter,
ordered the bishop of the south Saxons to remove his see from Selsey to
Chichester; the Wilts and Dorset bishop to remove his _cathedra_ from
Sherborne to Old Sarum, and the Mercian bishop, whose _cathedra_ was
then at Lichfield, to transfer it to Chester. Traces of the tribal and
migratory system may still be noted in the designations of the Irish see
of Meath (where the result has been that there is now no cathedral
church) and Ossory, the cathedral church of which is at Kilkenny. Some
of the Scottish sees were also migratory.

By the canon law the bishop is regarded as the pastor of the cathedral
church, the _parochia_ of which is his diocese. In view of this,
canonists speak of the cathedral church as the one church of the
diocese, and all others are deemed chapels in their relation to it.

Occasionally two churches jointly share the distinction of containing
the bishop's _cathedra_. In such case they are said to be con-cathedral
in relation to each other. Instances of this occurred in England before
the Reformation in the dioceses of Bath and Wells, and of Coventry and
Lichfield. Hence the double titles of those dioceses. In Ireland an
example occurs at Dublin, where Christ Church and St Patrick's are
jointl