Charles Ellicott Commentary Joel 2:28

"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, your young men shall see visions:" — Joel 2:28 (ASV)

I will pour out my spirit upon all flesh.—Holy Scripture itself is the interpreter of this most weighty promise. St. Peter’s quotation and application of it in Acts is its commentary.

The word Afterward from the original prophecy—which the Septuagint (LXX) translates as after these things—becomes, in the apostle’s words, in the last days. This latter phrase, in the last days, signifies the Christian dispensation, which began when, after the punishment of the Jews by the heathen, their king came.

The promise continues with the term my Spirit. St. Peter renders this as of my spirit (following the Septuagint), indicating the gifts and influences of the Holy Ghost. This Spirit is to be poured out upon all flesh—that is, without distinction of race or person.

Thus, they of the circumcision were astonished, because that on the Gentiles also was poured out the gift of the Holy Ghost. The outward manifestation of these gifts, as shown on the Day of Pentecost and in accordance with this prediction, was gradually withdrawn from the Church; the reality remains.