The Holy Spirit is often overshadowed by discussions surrounding Jesus, and even the Father, but in a way this is by design and the “order” of God’s life internal to himself. There are many important aspects of the Holy Spirit’s work though that we shouldn’t overlook, particularly with reference to, of course, thought about the Holy Trinity and the interior life of God. Thomas F. Torrance has these insightful things to note; as usual Torrance focuses in on the role that the reality of the homoousion brings to bear on a doctrine of the Holy Spirit:
It is by reference to this epistemological centre in the incarnate Son or Word mad flesh – that is, to the homoousion of the Son and the hypostatic union of divine Nature and human nature in him – that we also clarify our knowledge of the Spirit. He is not knowable in his own distinctive Person or hypostasis in the same way, for he is not embodied, like the incarnate Son, in the concrete modalities and structured objectivities of our world of space-time, or, like him, therefore, brought within the range of our human knowing at our lowly creaturely level. The Holy Spirit is God of God but not man of man, so that our knowledge of the Holy Spirit rests directly on the ultimate objectivity of God as God, unmediated by the secondary objectivities of space and time, and it rests only indirectly on those objectivities through relation to the Son with whom he is of one being as he is with the Father. Through all of God’s self-revelation to us in the incarnate Son, the Holy Spirit is the creative Agent in mediating knowledge of God to us in himself and the creative Agent in our reception and understanding of that revelation, although he is not himself the Word (λόγος) of that revelation or the Form (εἶδος) which that revelation assumes in Jesus Christ as it comes from the Father and is appropriated by us. But because it is in the Spirit as the immediate presence and power of God’s revelation to us that we know God in this way, the Father through the Son and the Son from the Father, we know the Spirit in himself as Lord God no less than the Father and the Son, who therefore with the Father and the Son together is worshipped and glorified. It is through holding constantly in our though the inseparable unity between the economic activity of God in the Spirit and the economic activity of God in the Son that we may be prevented from reading back into God himself the material or creaturely images (e.g. latent in human father-son relations) that rise out of the reciprocity he has established with us through the incarnation of his Son in space and time as one with us and one of us. Through the oneness of the Son and the Spirit the imaging of God in Jesus the incarnate Son or the Word made flesh is signitive, not mimetic. Thus the creaturely images naturally latent in the forms of thought and speech employed by divine revelation to us are made to refer transparently or in a diaphanous way to God without being projected into his divine Nature.
It takes at least a minute or two to try and comprehend what Torrance is getting at; particularly in the last few clauses of the paragraph. Essentially, I think Torrance is underscoring how there remains a type of ‘gulf’—a Creator/creature distinction—between us and the ineffable God. Such that the work of the Holy Spirit is, in part, to provide the accommodating context between God who is ultimate, and those of us who are not. His work is to create the union between God and humanity where this can happen in hypostatic union—so His overshadowing of Mary’s womb. It is this dynamic, back-and-forth in dialectic, wherein us humans, as we participate in and from the vicarious humanity of Jesus Christ, by the Holy Spirit, are able to actually make our way through the diaphanous humanity of Christ—like the torn veil of his broken and now resurrected body for us—into the very recess of God’s eternal, Holy, and Triune life. But it is, as Torrance develops, the work of the Holy Spirit to constantly mediate us into the mediating humanity of Christ; a humanity that finds its breath life in the antecedent and eternal life of the Divine Logos, the eternal ingenerate Son, Jesus Christ. It is as if the Holy Spirit, in a way, is the like the cleft of the rock that Moses was hidden in as he encountered the back side of God’s intensely burning shekinah presence; it’s just now that because of the Holy Spirit we are now ‘hidden’ (Col. 3) in the vicarious humanity of Christ, the eikon of God (Col 1.15) wherein an elevation has happened (Eph. 1.18-23). Through the mediatorial humanity of Christ, by the Spirit, we are able to look into the eyes of Godself by gazing into the face of Christ (II Cor. 4.5-6); we are now robed in his humanity, by the Spirit, which allows us to literally and ontologically sit at the right hand of the Holy Father, in the Son, and to participate and partake in the divine nature itself, by the grace of the Spirit, carrying out our priestly roles as coheirs with Christ, and sons and daughters of the King.
These are things and realities, in many ways, that we can only marvel in outright worship at. Realities that we can taste and see are good by participating in them; we can only talk about them to just an extent. But then again, that’s the point of all this; the Holy Spirit in and through the vicarious humanity of Christ, is in the constant mode of accommodating these deep and ineffable realities about God’s life into our lives in and through the creaturely modalities and creational structures we find ourselves currently enrobed by. The evangel is that because of who God is, Triune Love and Grace, he has bent down to us, and continuously does so by the work and person of the Holy Spirit, in and through the Sabbath rest of the Holy Son; our brother and Savior, Jesus Christ. amen.
 Thomas F. Torrance, The Christian Doctrine of God: One Being Three Persons (London: Bloomsbury T&T Clark, 2016), 101.