BRIEF YOEL INTRO
According to the Midrash (Bamidbar Rabbah 10:5) quoted by Rashi at the start of Yoel, Yoel was actually the son of Shmuel Hanavi. And though he is called ‘son of Petuel,’ this is merely a form of acronym for the fact that his prayer as effective (pittah kel betfillato). Thus, he prophesised in the days of Yehuram ben Achav in the days of the First Beis Hamikdash (over 300 years before its destruction). But in the Seder Olam, Yoel is put as prophesising during the days of Menasheh son of Chizkiyah (50 years before the churban), and as such was the disciple of Michah the prophet.
Yoel first prophesises about the forthcoming plague of locusts and ensuing famine, then speaks about forthcoming bracha and the days of Moshiach.
