tively constituted until the uniting of the three orders of
cardinals into a single body, the body which was to elect the pope; and
this only took place in the 12th century. Up till that time the elements
remained distinct, and there were separate classes: the "Roman" bishops,
i.e. bishops of sees near Rome, presbyters of the "titles" (_tituli_) of
Rome, and deacons of the Roman Church. Nowadays, the Sacred College is
still composed of three orders or categories: cardinal bishops, cardinal
priests, and cardinal deacons. But the process of evolution has not been
the same in the case of all these orders.

Cardinal bishops.

Cardinal bishops are the bishops of suburbicarian churches, situated in
the immediate neighbourhood of Rome. Very early we find them assisting
the pope in his ritual functions and in dealing with important business;
they formed a kind of permanent synod (cf. the [Greek: synodos
endemousa] of Constantinople): and they also took the place of the pope
in the ceremonies of the liturgy, excepting the most important ones, and
especially in the service of the cathedral at Rome, the Lateran. A
passage from the life of Stephen II. (A.D. 769), in the _Liber
Pontificalis_ (ed. Duchesne, i. p. 478), shows clearly that they were
seven in number and served for a week in turn: _Hic constituit ut omni
dominico die a septem Episcopis cardinalibus hebdomadariis, qui in
ecclesia Salvatoris_ (the Lateran) _observant, missarum solemnia super
altare Beati Petri celebrarentur_. They were called "cardinal bishops of
the Lateran church," as recorded by St Peter Damian in 1058 (Ep. 1, lib.
ii.). Their sees are the same to-day as they were then: Ostia, Porto,
Santa Rufina (Sylva Candida), Albano, Sabina, Tusculum (Frascati) and
Palestrina. From time immemorial the bishop of Ostia has had the
privilege of sacring the pope, and on this ground he enjoys the right of
wearing the "pallium"; he is _ex officio_ dean of the suburbicarian
bishops, and consequently dean of the Sacred College. His episcopal see
having been in ruins for a long time, that of Velletri has been joined
to it. The second rank belongs to the bishop of Porto, who is _ex
officio_ vice-dean of the Sacred College; his episcopal see being also
in ruins Calixtus II. added to it that of Santa Rufina, thus reducing
the number of suburbicarian bishoprics and cardinal bishops to six; this
number was adhered to by Sixtus V., and has not varied since.

Cardinal pri