udic. 21 Tertullian already defines the position of his adversary by
the saying, "ecclesia est numerus episcoporum.") This episcopate by its
unity guarantees the unity of the Church and has received the power to
forgive sins (Cyp., ep. 69. 11).

The new conception of the Church, which was a necessary outcome of
existing circumstances and which, we may remark, was not formulated in
contradictory terms by Cyprian, but by Roman bishops,[238] was the first
thing that gave a fundamental _religious_ significance to the separation
of clergy and laity. The powers exercised by bishops and priests were
thereby fixed and hallowed. No doubt the old order of things, which gave
laymen a share in the administration of moral discipline, still
continued in the third century, but it became more and more a mere form.
The bishop became the practical vicegerent of Christ; he disposed of the
power to bind and to loose. But the recollection of the older form of
Christianity continued to exert an influence on the Catholic Church of
the third century. It is true that, if we can trust Hippolytus' account,
Calixtus had by this time firmly set his face against the older idea,
inasmuch as he not only defined the Church as _essentially a mixed body_
(_corpus permixtum_), but also asserted the unlawfulness of deposing the
bishop even in case of mortal sin.[239] But we do not find that
definition in Cyprian, and, what is of more importance, he still
required a definite degree of active Christianity as a _sine qua non_ in
the case of bishops; and assumed it as a self-evident necessity. He who
does not give evidence of this forfeits his episcopal office _ipso
facto_.[240] Now if we consider that Cyprian makes the Church, as the
body of believers (_plebs credentium_), so dependent on the bishops,
that the latter are the only Christians not under tutelage, the demand
in question denotes a great deal. It carries out the old idea of the
Church in a certain fashion, as far as the bishops are concerned. But
for this very reason it endangers the new conception in a point of
capital importance; for the spiritual acts of a sinful bishop are
invalid;[241] and if the latter, as a notorious sinner, is no longer
bishop, the whole certainty of the ecclesiastical system ceases.
Moreover, an appeal to the certainty of God's installing the bishops and
always appointing the right ones[242] is of no avail, if false ones
manifestly find their way in. Hence Cyprian's idea of