In order to clarify this question it is necessary to distinguish (of course, in the abstract) the immanent Trinity from the economic Trinity, the supra-eternal life of the Holy Trinity in Itself from Its trihypostatic revelation in creation. Let us first investigate trinitarity in its immanent aspect. Here, Revelation gives us the fact of the divine triunity of the Father, Son, and Spirit: Unity in Trinity and Trinity in Unity, the one Name, the one God the Holy Trinity. Not three in unity, but triunity; and not one, but unifiedness in Trinity. This is the divine number, which does not exist in the natural world, but which is a super-number for the latter: the three in one. This super-number refers not to things, which can be counted in their separateness and juxtaposition, but to the Divine Person or Persons, Who has or have one unified, but not common, natural life.

Personal consciousness of self is proper to the nature of spirit: “I am that I am,” Jehovah, says the Lord. Spirit is, above all, personality as personal consciousness of self, as “I.” An impersonal (“unconscious”) spirit is a contradiction. But this I is not an abstract self-consciousness that is not connected with anything and empty for itself (even the dreaming I of Hinduism at least has its dream and lives in it). It is a living I (“I am that I am”), the subject of a certain objectivity, the subject of a certain predicate, the receptacle of a certain content. The living I has its own life. It is the source of this life and its fullness, its beginning and end. The personal spirit thus has in itself its own nature, in which it lives, ceaselessly realizing itself for itself through this nature, defining itself and revealing itself to itself. This indissoluble unity of the personal self-consciousness, of I and its nature, grounding the life of the personal spirit, is the spirit's limiting intuition of itself and also the initial ontological axiom. … God possesses personality and nature, hupostasis, phusis, or ousia. As a result, God is a hypostasis that has its own nature, and precisely in this sense He is a living personal spirit. Such a definition of personal spirit is applicable to any spirit, divine, angelic, or human. The distinctive property of the Divine Spirit is that this Spirit is not only a personal but also a trihypostatic spirit, a trihypostatic personality, which, however, has one nature and, accordingly, one life (not a life in common, but precisely one life), just as every unihypostatic spirit has one nature and one life.

The spirit of God is the triunity of the three hypostases in the separateness of Their Persons. The Holy Spirit is Their hypostatic union in the Third Person. If one can say, on the basis of the principle of the monarchy of the Father, that the entire Holy Trinity is the Father Who reveals Himself in the Son and the Spirit, one can also speak about the divine triunity of the Divinity revealed in the hypostasis of the Holy Spirit. In the first case the Father is autotheos or ho Theos, God the Subject; in the second case, one can say about the Third hypostasis that it is the Spirit of the spirit, to pneuma (with an article), in relation to Theion pneuma, a predicate (or even copula) that has become its own subject. In the fullness and perfection of His self-revelation, God is the Third and final hypostasis, which in this sense is, as it were, also the First hypostasis.

God is Spirit. As such, He has a personal consciousness of self (“hypostasis”) and a nature (“ousia”); and this inseparable union of nature and hypostasis is the life of Divinity in itself, a life that is both personally conscious and naturally concrete. This interrelation between hypostasis and nature, their inseparable union, is proper to both …

In relation to the hypostasis of God as the Absolute Subject, there is the trihypostatic personality, which in one personal consciousness of self unites all the modes of the personal principle I, thou, he, we, and you; whereas a unihypostatic personality has all these modes except I outside itself, in other personalities, and is thus limited and conditioned by them in its being. Fully manifested and actualized, the personal principle, the hypostasis, is a trihypostatic personality, in which the personal unity is revealed in the reality of three hypostatic centers, or hypostases, in triunity. Trinity is the divine number, not three and not one, but precidely triunity, Trinity. Such hypostatic being is realized not statically, as the uni-personal self-consciousness of the separate, isolated I in itself, reposing in its self-givenness (although this static and self-finished character is only apparent, for every I goes out into thou, we, you); rather it is realized dynamically, as the eternal act of trinitarian self-positing in another. This dynamic self-positing is love: the flames of the divine trihypostasis flare up in each of the hypostatic centers and are then united and identified with one another, each going out of itself into the others, in the ardor of self-renouncing personal love. Statically, the unihypostatic personality is the center of self-affirmation and of repulsion; it is egocentric. Dynamically, the personality actualizes itself as the initial principle of self-renouncing love, as the going out into another I. The Holy Trinity as a personality is precisely such a dynamic personal principle. In it, the static being of each personal center is the initial principle of the dynamic going out, where personal self-affirmation is removed and overcome, and the Person is realized as the ring of this trinitarian self-moving love. Therefore, the first thing one must say about the Divine Person is that, as trihypostatic, this Person is equally real in one hypostasis and in three hypostases, that this Person is the pre-eternally realized reciprocity of love that totally vanquishes personal isolation and identifies three in one, while itself existing by the real being of these personal centers. [On this subject, as well as on the further considerations in the present chapter, see my work «Chapters on Trinity». I will not repeat the discussion in that work here.]

The trihypostatic Divinity is one Person, despite this trihypostatizedness, or rather in virtue of it. And in this unity of its personality (which nevertheless is not a monohypostatizedness) the Divine spirit does not formally differ from the creaturely spirit. And the Divine Person lives, actualizing His life in His nature. The one trihypostatic Divine Person has His divine nature — that is the fundamental definition of the Church. The trihypostatic God has His one nature, and He has this nature both as the Divine triunity in its unicity and as each hypostasis in its being: not only is the Son “consubstantial” with the Father (which was precisely the subject of dispute in the Arian epoch) but the Holy Spirit is «consubstantial» with the Father and with the Son. TThe three hypostases have their nature not in common, not in common possession (nor do they have it each one for Himself, which would be tritheism), but as one for all, homoousianly, not homoiousianly. In the domain of the theoretical reason, or rationality, this can be expressed only in equalities of the unequal: (1a) the Holy Trinity differs from each hypostasis, is not equal to it; (1b) the Holy Trinity is equidivine with respect to each hypostasis and consequently is equal to it; (2a) the Holy Trinity possesses one nature; (2b) each hypostasis also possesses one nature; consequently, the possession of one nature is equal and different for the Holy Trinity and each individual hypostatsis. These rational contradictions, to which this idea is reduced, can be explained by the fact that rational thought deals with static quantities that are posited externally in their finished facticity, whereas here it is faced with acts that are fluid in their dynamicity and continuity. These acts are therefore not subject to rational thought; they are not exhausted by its schemata.