The Holy Spirit reveals the Son 

Just as the Son revealed the Father, so the Holy Spirit reveals him. These are the words of our Lord, “And he will bring honor to me because it is from me that he will derive what he makes plain to you, because all that belongs to the Father belongs to me.” In these words our Blessed Lord is saying that once he ascends to the Father, then all of the spiritual blessings won by him on Calvary will be conveyed to us by the Holy Spirit. Jesus said during his earthly life that we would not understand his life, we would not receive all of the merits of his life until the Spirit came to this earth. The great business of the Holy Spirit, therefore, is to stand behind the scenes to make Christ more real. That is why the apostles did not understand the crucifixion until after Pentecost. St. Paul goes so far as to say that no one can call Jesus “Lord” except by the Spirit. Oh, sure, you can pronounce the word Jesus, but you do not know that Jesus is the Christ, the Son of God, the Savior of the world, the Lord of the universe, except by the Holy Spirit.