2:14-21 Peter's sermon shows that he was thoroughly recovered from his fall, and thoroughly restored to the Divine favour; for he who had denied Christ, now boldly confessed him. His account of the miraculous pouring forth of the Spirit, was designed to awaken the hearers to embrace the faith of Christ, and to join themselves to his church. It was the fulfilling the Scripture, and the fruit of Christ's resurrection and ascension, and proof of both. Though Peter was filled with the Holy Ghost, and spake with tongues as the Spirit gave him utterance, yet he did not think to set aside the Scriptures. Christ's scholars never learn above their Bible; and the Spirit is given, not to do away the Scriptures, but to enable us to understand, approve, and obey them. Assuredly none will escape the condemnation of the great day, except those who call upon the name of the Lord, in and through his Son Jesus Christ, as the Saviour of sinners, and the Judge of all mankind.

17. in the last days—meaning, the days of the Messiah (Isa 2:2); as closing all preparatory arrangements, and constituting the final dispensation of God's kingdom on earth.

pour out of my Spirit—in contrast with the mere drops of all preceding time.

upon all flesh—hitherto confined to the seed of Abraham.

sons … daughters … young men … old men … servants … handmaidens—without distinction of sex, age, or rank.

see visions … dream dreams—This is a mere accommodation to the ways in which the Spirit operated under the ancient economy, when the prediction was delivered; for in the New Testament, visions and dreams are rather the exception than the rule.