It is not known exactly when the prophet Joel began his work as a prophet. However, it is known that during his life a terrible catastrophe befell the land. A swarm of locusts, surpassed only by the plague of locusts in Egypt during the days of Moses, descended upon the fields and vineyards and devoured everything green. This is how the prophet describes the dreadful devastation of the land: "The word of the L-rd that came to Joel the son of Pethuel: Hear this, ye old men, and give ear, all ye inhabitants of the land I Did ever such a thing as this come to pass in your days, or ever in the days of your fathers?... It (the locust) has laid my vine waste, and barked my fig-tree; it has peeled it bare and cast it down; made white are its light branches... Wasted is the field; the land mourns; for wasted is the corn, dried up is the new vine, and withered is the oil... Joy has ceased from the children of men."

The prophet sees in this calamity a severe punishment from G‑d for Israel's faithlessness in Him and His laws, and he calls to his brethren to return. "Yet even now, saith the L-rd, turn ye unto Me with all your heart, and with fasting, and with weeping, and with lamentation; rend your heart, and not your garments, and turn. unto the L-rd your G‑d; for He is gracious and compassionate, long-suffering, and abundant in mercy, and relenteth of the evil... Blow the shofar in Zion, sanctify a fast, and proclaim a solemn assembly! Gather the people, sanctify the congregation, assemble the elders, and gather the children and babies... let them say, 'Spare, O L-rd, Thy people, and give not Thy heritage to shame, for nations to rule over them! Why should they say among the people. 'Where is their G‑d?'"

But almost in the same breath the prophet predicts wonderful things for his people; G‑d will repay them for their suffering manifold. "And ye shall eat and be satisfied, and praise the Name of G‑d, your L-rd, Who has dealt wondrously with you; and my people shall not be made ashamed unto eternity. And you shall know that I am in the midst of Israel, and that I am G‑d, your L-rd, and none else; and My people shall not be ashamed unto eternity."

After Israel's triumph, Joel foresees the day when all mankind, even men and women of the lowest station in life, shall have the knowledge and vision of G‑d: "And it shall come to pass afterward that I will pour out My spirit upon all flesh; and your sons and your daughters shall prophesy; your old men shall dream dreams and your young men shall see visions; and also upon the servants and upon the handmaidens in those days will I pour out My spirit."