Summary: The article deals with the notion of order between the divine Persons, which is as basic for the Trinitarian Greek theology, as it is with the concept of relation for the Western doctrine, but especially for Thomas Aquinas, while the profoundly Latin theology of John Duns Scotus is nearer to the Greek thaught. The Eastern Fathers are convinced that the order has been indicated by the Lord Jesus himself, as he sent the apostles to teach and baptize all the nations “in the name of the Father and of the Son and of the Holy Spirit” (Mt. 28, 19). In this view, the succession of the holy names is immutable, because it emerges from the link of origin, i. e. from the reference between a Person, who proceeds, to another, from whom she receives her proper existence. It explains the current Greek theological linear outline, where the Son is placed between the Father and the Holy Spirit, and demostrates that the relation of the Spirit to the Son must be as real link of origin, as the reference of the Son to the Father. This is the meaning of the ancient Greek formula, according to which the Holy Spirit proceeds ‘from the Father through the Son’, therefore also from the Son; what preliminarily reveals the error diffused in the IX century in Byzantium by patriarch Photius, who maintained that the Spirit poceeds ‘only from the Father’.