Gregory of Nazianzus — as excerpted in the Catena Aurea on Luke 11:33-36

“(Epist. 41.) Or else; The light and eye of the Church is the Bishop. It is necessary then that as the body is rightly directed as long as the eye keeps itself pure, but goes wrong when it becomes corrupt, so also with respect to the Prelate, according to what his state may be, must the Church in like manner suffer shipwreck, or be saved.”