9 Let us see then how the Ninevites fasted, and how they were delivered from that wrath— “Let neither man nor beast, herd nor flock, taste anything,” says (the prophet). What do you say? Tell me— must even the irrational things fast, and the horses and the mules be covered with sackcloth? “Even so,” he replies. For as when, at the decease of some rich man, the relatives clothe not only the men servants and maid servants, but the horses also with sackcloth, and give orders that they should follow the procession to the sepulchre, led by their grooms; thus signifying the greatness of the calamity, and inviting all to pity; thus also, indeed, when that city was about to be destroyed, even the irrational nature was enveloped in sackcloth, and subjected to the yoke of fasting.
“It is not possible,” says he, “that irrational creatures should learn the wrath of God by means of reason; let them be taught by means of fasting, that this stroke is of divine infliction. For if the city should be overturned, not only would it be one common sepulchre for us, the dwellers therein, but for these likewise. Inasmuch then as these would participate in the punishment, let them also do so in the fast.” But there was yet another thing which they aimed at in this act, which the prophets also are wont to do.
For these, when they see some dreadful chastisement proceeding from heaven, and those who are to be punished without anything to say for themselves—laden with shame—unworthy of the least pardon or excuse:— not knowing what to do, nor from whence they may procure an advocacy for the condemned, they have recourse to the things irrational; and describing their death in tragical fashion, they make intercession by them, putting forward as a plea their pitiable and mournful destruction.
When therefore, aforetime, famine had seized upon the Jews, and a great drought oppressed their country, and all things were being consumed, one of the prophets spoke thus, “The young heifers leaped in their stalls; the herds of oxen wept, because there was no pasture; all the cattle of the field looked upward to You, because the streams of waters were dried up.” Another prophet bewailing the evils of drought again speaks to this effect: “The hinds calved in the fields and forsook it, because there was no grass.
The wild asses stood in the forests; they snuffed up the wind like a dragon; their eyes did fail, because there was no grass.” Moreover, you have heard Joel saying today, “Let the bridegroom go forth of his chamber, and the bride out of her closet;— the infants that suck the breast.” For what reason, I ask, does he call so immature an age to supplication? Is it not plainly for the very same reason? For since all who have arrived at the age of manhood, have inflamed and provoked God's wrath, let the age, says he, which is devoid of transgressions supplicate Him who is provoked.
Source: Homilies on the Statues (New Advent)