It must needs be, not absolutely, but the weakness and wickedness of the world considered that scandals should happen. (Witham)

Considering the wickedness and corruption of the world, such things always will happen; but the judgments of God, though slow, will be terrible in the extreme. Lento quidem gradu Divina procedit Vindicta, sed tarditatem gravitate compensat. (Val. Max.)

We must not suppose for a moment that Christ subjects human actions to the control of rigid fatality. It is not the prescience or prediction of Christ, which causes these evils to take place; they do not happen, because Christ foretold them; but, Christ foretold them, because they would infallibly happen. The Almighty permits scandals, because the good are benefited by them, making them more diligent and more watchful: witness the great virtue of Job, of Joseph, and many others perfected in temptation. If the less virtuous receive any detriment from scandals, they owe it to their own sloth and laziness. (St. Chrysostom, hom. lx.)

Jesus Christ pronounces a double wo to the man who bringeth scandal, and to the world which is punished by it. But why, asks St. Chrysostom does he bewail the miseries of the world, when it depended upon him to stretch forth his hand and remove them? He imitates the conduct of a good physician, who, after prescribing various remedies, feels himself obliged to declare to his patient, that by neglecting the prescriptions, he is increasing his distemper. Jesus Christ had left the throne of his glory, taken upon him the form of a servant, and suffered the greatest extremities, but seeing man so perverse as to reap no advantage from all he had done and suffered for him, he weeps over his miserable state. Nor is this without its particular fruit; for it frequently happens, that whom good counsel cannot move, prayers and tears, and the relation of the dismal consequences attendant on sin, bring to repentance. This also manifests his tenderness and boundless charity, since he weeps over the people, who of all others most contradicted him. (St. Chrysostom, hom. lx.)