The Book of Joel is one of the “Scroll of the 12,” or one of the so-called Minor Prophets. This doesn’t mean that Joel and the other 11 are not important (this includes Hosea and Amos, for example), but that the oracles of these 12 prophets can all fit on one scroll. Joel was written about 400 BC and its main theme is the “Day of the Lord.” There had been a devastating plague of locusts and Joel saw this as a metaphor for the “Day of the Lord,” a day of judgment. So, he called the people to repentance. We read from Joel every Ash Wednesday.