“I have told you this while I am with you. The Advocate, the Holy Spirit, whom the Father will send in my name, will teach you everything and remind you of all that I told you."
God is the author of Sacred Scripture. "The divinely revealed realities, which are contained and presented in the text of Sacred Scripture, have been written down under the inspiration of the Holy Spirit." "For Holy Mother Church, relying on the faith of the apostolic age, accepts as sacred and canonical the books of the Old and the New Testaments, whole and entire, with all their parts, on the grounds that, written under the inspiration of the Holy Spirit, they have God as their author, and have been handed on as such to the Church herself."
-- CCC 105
Before his Passover, Jesus announced the sending of "another Paraclete" (Advocate), the Holy Spirit. At work since creation, having previously "spoken through the prophets", the Spirit will now be with and in the disciples, to teach them and guide them "into all the truth". The Holy Spirit is thus revealed as another divine person with Jesus and the Father.
-- CCC 243
The Spirit and the Church cooperate to manifest Christ and his work of salvation in the liturgy. Primarily in the Eucharist, and by analogy in the other sacraments, the liturgy is the memorial of the mystery of salvation. The Holy Spirit is the Church's living memory.
-- CCC 1099
On the day of Pentecost, the Spirit of the Promise was poured out on the disciples, gathered "together in one place." While awaiting the Spirit, "all these with one accord devoted themselves to prayer." The Spirit who teaches the Church and recalls for her everything that Jesus said was also to form her in the life of prayer.
-- CCC 2623