But let man and beast be covered with sackcloth, and cry mightily unto God: yea, let them turn every one from his evil way, and from the violence that is in their hands.
Read Chapter 3
They had a covering of sackcloth at a time when, since all were mourning over the approaching destruction of the city and were clothed with the same garments, none could be accused of excessive display. (Institutes Bk 1.2)
Recall that Daniel, passionate man though he was, spent many days fasting. He received as recompense an awesome vision so that he tamed the fury of the lions and turned them into the mildest of sheep, not by changing their nature but by diverting their purpose without loss of their ferocity. The Ninevites too made use of the remedy of fasting and won from the Lord a reprieve. Animals as well as human beings were included in the fast, so that all living things would abstain from evil practices. This total response won the favor of the Lord of all.
Coarseness of attire is sometimes a sign of sorrow: wherefore those who are in sorrow want to wear coarser clothes, just as on the other hand in times of festivity and joy they wear finer clothes. Just as a man’s mind is uplifted by fine clothes, so is it humbled by lowly apparel.