Joel was a prophet whose oracles announced both locust-plague devastation and coming restoration. Acts 2:16 quotes Joel 2:28-32 as Peter explains the Pentecost outpouring: 'This is what was spoken by the prophet Joel.' Joel's vision of the Spirit poured out on all flesh—sons and daughters prophesying, the old and young seeing visions—finds its initial fulfillment in the upper room. The citation authorizes the charismatic phenomena as divinely promised, not aberrant.