“But the hireling, and he that is not the shepherd, whose own the shee; are not, seeth the wolf coming, and leaveth the sheep, and flieth: and the wolf casteth, and scattereth the sheep” (Jn 10:12).
Hirelings are not wolves, nor do they resist them. Hirelings merely seek their own. That is why they are not true shepherds. In times of peace, they look the same as true shepherds. When the going gets tough, they abandon the sheep.
How? À Lapide comments, citing Pope St. Gregory, The Great:
“ ‘Not by change of place but by withdrawing support.’ He flies, because he saw injustice and remained silent: He flies because he conceals himself by silence…. Hence Christ leaves it to be gathered by contrast that the good shepherd, when he sees the wolf coming, neither flies nor forsakes his sheep, but stands up for them and fights even to death, and in this way lays down his life for them…. [Gregory states,] ‘He who loves not the sheep but worldly gain, cannot stand firm when the sheep are in danger. For while he is aiming at honor, and rejoicing in worldly gain, he is afraid of exposing himself to danger, lest he should lose that which he love.”