J.I. Packer writes:
The Holy Spirit’s distinctive new covenant role, then, is to fulfil what we may call a floodlight ministry in relation to the Lord Jesus Christ. So far as this role was concerned, the Spirit “was not yet” (John 7:39, literal Greek) while Jesus was on earth; only when the Father had glorified him (see John 17:1, 5) could the Spirit’s work of making men aware of Jesus’ glory begin.
I remember walking to a church one winter evening to preach on the words “he shall glorify me,” seeing the building floodlit as I turned a corner, and realizing that this was exactly the illustration my message needed.
When floodlighting is well done, the floodlights are so placed that you do not see them; you are not in fact supposed to see where the light is coming from; what you are meant to see is just the building on which the floodlights are trained. The intended effect is to make it visible when otherwise it would not be seen for the darkness, and to maximize its dignity by throwing all its details into relief so that you see it properly. This perfectly illustrates the Spirit’s new covenant role. He is, so to speak, the hidden floodlight shining on the Saviour.
Or think of it this way. It is as if the Spirit stands behind us, throwing light over our shoulder, on Jesus, who stands facing us.
The Spirit’s message is never,
“Look at me;
listen to me;
come to me;
get to know me,”
“Look at him, and see his glory;
listen to him, and hear his word;
go to him, and have life;
get to know him, and taste his gift of joy and peace.”
~ from Keep in Step with the Spirit: Finding Fullness in Our Walk with God