Tom Nettles on the Double Procession of the Holy Spirit

"How does the Holy Spirit proceed eternally? What is the relationship of the Spirit to the Father and the Son?

"Well there was massive theological discussion between the church in the West and the church in the East, and the church in the West decided that for a biblical understanding of the language about the Father sending the Spirit through the Son, or the Son sending the Spirit, or the Spirit being called the Spirit of the Father and also being called the Spirit of the Son, and because of the functions of the Spirit in taking the things of Christ and showing them to us, glorifying Christ, etc., it was seen to be the necessary biblical witness that in their eternal relationship, the Holy Spirit, in order to maintain His distinctive spirituality and not sonship nor fatherhood, must be described as proceeding not just from the Father, but from the Father and the Son [as] the perfect bond of unity. And they would say this is what is behind Paul being able to affirm in Colossians [3:14], "Love, which is the perfect bond of unity." [See Jonathan Edwards on this point.] This has to do with the Spirit proceeding from the Father and the Son as a continued manifestation of infinite love."