A sequence is a long hymn or sacred poem that is inserted after the second reading and before the Gospel Acclamation (Alleluia!). These hymns are intended to reinforce the sanctity of the particular solemnity or feast that is being celebrated that day. For instance, the Victimae Paschali Laudes sequence during Easter week retells the story of Mary Magdalene finding the empty tomb, while the Veni Sancte Spiritus of Pentecost calls down the Holy Spirit upon the congregation. These sequence poems date back to the Middle Ages, and were most often set to music which would reflect the joyful or somber mood of the occasion.