...but he who has human beings entrusted to him, the rational flock of Christ, incurs a penalty in the first place for the loss of the sheep, which goes beyond material things and touches his own life: and in the second place he has to carry on a far greater and more difficult contest. For he has not to contend with wolves, nor to dread robbers, nor to consider how he may avert pestilence from the flock. With whom then has he to fight? With whom has he to wrestle? Listen to the words of St. Paul: 

(Regarding wolves in sheep's clothing): ....even should they capture the whole flock, they do not leave the shepherd unmolested, but attack him all the more, and wax bolder, ceasing not until they have either overthrown him, or have themselves been vanquished. Again, the afflictions of sheep are manifest...