Calvin’s account of the manifold of mutually co-existing Persons or of real hypostatic relations subsisting within the one indivisible Being of the Godhead is very similar to that of Gregory Nazianzen, although he does not use the explicit language of perichoresis or its Latin equivalent (circumincessio). After citing Gregory Nazianzen in support, he says: “Let us not imagine a Trinity of Persons in such a partitive way that our thought is not immediately brought back to that Unity. The words ‘Father,’ ‘Son,’ and ‘Holy Spirit’ certainly import a real distinction – let us not think they are mere epithets by which God is variously designated from His works – it is a distinction, however, not a division” (Institutes 1.13.7, with reference to Gregory Nazianzen, Oratio 40.41). Although it is only with the advent of Christ that the distinctions between the Persons are revealed, they are to be understood as existing antecedently and inherently in the Godhead who may not be known otherwise than as three distinct Persons co-existing in one Being. As we have seen, he accepts, like Gregory Nazianzen that, while there is no before or after in these Trinitarian relations, there is a significant order within them: “the Father first, then the Son from Him, and then the Spirit from both. . .the Son is said to exist from the Father only, the Spirit from both the Father and the Son (a Patre simul et Filio) (Institutes 1.13.18 and 20).*
*It would be better to say that “the Son is sent into the world by the Father only and that the Spirit is sent into the world by both the Father and the Son.” As fully divine themselves, neither the Son nor the Spirit are dependent on the Father for their existence – one Being, Three Persons.
From: Trinitarian Perspectives: Toward Doctrinal Agreement by Thomas F. Torrance (Edinburgh: T&T Clark, 1994), p. 34.