On the Day of Pentecost, the Spirit was poured out in unlimited measure, fulfilling Jesus' earlier promise:

“But you will receive power when the Holy Spirit comes on you; and you will be my witnesses . . . to the ends of the earth.”
—Acts 1:8.

The Spirit assumed the form of a dove at Christ's baptism. At Pentecost He appeared as “tongues of fire that separated and came to rest on each of them” (Acts 2:3). On that occasion the Spirit enabled the apostles to communicate the gospel clearly in the languages of people “from many nations” (verses 4-6).

Some Bible students compare the coming of the Spirit to the falling of the early autumn and the late spring rains of Palestine.

“Be glad, O people of Zion, rejoice in the Lord your God, for he has given you the autumn rains in righteousness. He sends you abundant showers, both autumn and spring rains, as before.”
—Joel 2:23.

Early autumn in Palestine brings gentle rains which saturate the ground and water the seeds, causing new shoots to sprout from the soil. The Spirit falling at Pentecost was like the early rain of autumn. Pentecost watered the Word sown by Jesus during His ministry and the disciples caused many new buds of faith to spring up as they began to carry the gospel to all the world. This “early rain” of the Spirit provided vital nourishment for the Christian church in its infancy, watering a great many seeds (Joel 2:23, NIV & KJV).