Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls. And they continued stedfastly in the apostles’ doctrine and fellowship, and in breaking of bread, and in prayers. Acts 2:41, 42.
It is true that in the time of the end, when God's work in the earth is closing, the earnest efforts put forth by consecrated believers under the guidance of the Holy Spirit are to be accompanied by special tokens of divine favor. Under the figure of the early and the latter rain, that falls in Eastern lands at seedtime and harvest, the Hebrew prophets foretold the bestowal of spiritual grace in extraordinary measure upon God's church. The outpouring of the Spirit in the days of the apostles was the beginning of the early, or former, rain, and glorious was the result. To the end of time the presence of the Spirit is to abide with the true church.
But near the close of earth's harvest, a special bestowal of spiritual grace is promised to prepare the church for the coming of the Son of man. This outpouring of the Spirit is likened to the falling of the latter rain; and it is for this added power that Christians are to send their petitions to the Lord of the harvest “in the time of the latter rain.” In response, “the Lord shall make bright clouds, and give them showers of rain” (Zechariah 10:1). “He will cause to come down ... the rain, the former rain, and the latter rain” (Joel 2:23).
But unless the members of God's church today have a living connection with the Source of all spiritual growth, they will not be ready for the time of reaping. Unless they keep their lamps trimmed and burning, they will fail of receiving added grace in times of special need.—The Acts of the Apostles, 54, 55.
From Ye Shall Receive Power - Page 317
Ye Shall Receive Power