Q. How did the custom of imposing ashes come to be associated with penance?
A. In ancient Jewish culture, covering oneself with dust and ashes (usually accompanied by the wearing of sackcloth) was a customary gesture of intense grief. The dust and ashes symbolized having been brought low, all the way to the ground.
In the Old Testament, for example, Job covered himself in ashes after his children died and he was painfully afflicted with boils (Job 2:8). Mordecai and his fellow Jews put on sackcloth and ashes when they learned that the Persians were planning genocide against them (Esther 4:1–3). Jeremiah warned his people that God would judge them so severely, the women would “put on sackcloth, and roll in ashes” (Jeremiah 6:26).