'Veni Sancte Spiritus,' also known as the 'Golden Sequence,' is a sequence prescribed in the Roman Liturgy for the Masses of Pentecost. It's a beautiful, ancient hymn calling on the Holy Spirit. The text is attributed to either Pope Innocent III or Stephen Langton, Archbishop of Canterbury, in the early 13th century. Here are the traditional Latin lyrics along with an English translation:
Veni, Sancte Spiritus, et emitte caelitus lucis tuae radium.
Veni, pater pauperum, veni, dator munerum, veni, lumen cordium.