In the Office of Readings for Ascension Thursday, the long Scripture reading, and its responsory, are taken from the Letter to the Ephesians, chapter 4:
When Christ ascended on high, he led captivity captive, he gave gifts to men.
Interestingly enough, the gifts Christ gave were charisms, or rather persons with charisms, “apostle, prophets, evangelists, pastors, and teachers in roles of service.” According to Ephesians, it is these gifts of Christ’s that form us into Christ, “that perfect man who is Christ come to full stature.”
The Magnificat antiphon of the Ascension, the great O Rex Gloriae, is an epiclesis of the Holy Spirit. It is addressed, not to the Father, but to Christ.
O Victor King, Lord of power and might, today you have ascended in glory above the heavens. Do not leave us orphans, but send us the Father’s promised gift, the Spirit of truth, alleluia.
This is a subtle prayer. Addressed to Christ, it asks that He send us the Father’s promised gift. The gift of the Father, sent by the Son. The Spirit, sent by the Son, is thematic in the liturgy of these days. For example, the invitatory antiphon during this time, the Church’s original novena, is
Come, let us adore Christ the Lord who promised to send the Holy Spirit on His people, alleluia.
Examples such as this abound, as a quick glance through the breviary shows. The Son sends the Spirit.
But, why was it necessary that He first ascend?