Q. The Church calendar celebrates Pentecost 10 days after the Ascension. Is there any indication in the Bible of how long the interim really was? The Acts of the Apostles talks about the commissioning of Matthias between the two events, but not much else.
A. Here’s a reply from Father Reginald Martin:
Among our Hebrew ancestors, Pentecost was a joyous harvest festival, an opportunity to offer God the first fruits of the agricultural year. Some Jews still observe Pentecost as an agricultural feast today. The name “Pentecost” means “fiftieth day,” and because it was celebrated at the completion of the seven weeks after Passover, it became known in the Bible as The Feast of Weeks. In the Old Testament the feasts of Passover and Pentecost are ritually linked, Passover characterized by unleavened bread and Pentecost by leavened.
The Old Testament is a sad story of God’s withdrawal from his people, and no longer addressing them directly. John the Baptist and Jesus spoke like the old prophets, thus reviving a number of nearly forgotten hopes and dreams.
Peter makes this clear on the Day of Pentecost, when he tells those who had come to Jerusalem for the feast that Jesus (the Passover sacrifice) was now (at Pentecost) offering his Spirit, the fulfillment of all the scriptural promises. When the crowds asked what they must do to enjoy the promises, Peter replied, “Repent, and be baptized.” The Church continues the connection between the Old and New Testaments cemented by Jesus’ sacrifice and ratified at Pentecost.