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.

JFB.