[Carl Jung on The Trinity.]
As a psychological symbol the Trinity denotes, first, the homoousia or essential unity of a three-part process, to be thought of as a process of unconscious maturation taking place within the individual.
To that extent the three Persons are personifications of the three phases of a regular, instinctive psychic occurrence that always tends to express itself in the form of mythologems and ritualistic customs (for instance, the initiations at puberty, and the various rites for birth, marriage, sickness, war, and death).
As the medical lore of the ancient Egyptians shows, myths as well as rites have a psychotherapeutic value, and they still have today.
Second, the Trinity denotes a process of conscious realization continuing over the centuries.
Third, the Trinity lays claim not only to represent a personification of psychic processes in three roles, but to be the one God in three Persons, who all share the same divine nature.
In God there is no advance from the potential to the actual, from the possible to the real, because God is pure reality, the “actus purus” itself.
The three Persons differ from one another by reason of the different manner of their origin, or their procession (the Son begotten by the Father and the Holy Ghost proceeding from both procedit a patre filioque).
The homoousia, whose general recognition was the cause of so many controversies, is absolutely necessary from a psychological standpoint, because, regarded as a psychological symbol, the Trinity represents the progressive transformation of one and the same substance, namely the psyche as a whole.
The homoousia together with the filioque assert that Christ and the Holy Ghost are both of the same substance as the Father.
But since, psychologically, Christ must be understood as a symbol of the self, and the descent of the Holy Ghost as the self’s actualization in man, it follows that the self must represent something that is of the substance of the Father too.
This formulation is in agreement with the psychological statement that the symbols of the self cannot be distinguished empirically from a God-image.
Psychology, certainly, can do no more than establish the fact that they are indistinguishable.
This makes it all the more remarkable that the ”metaphysical” statement should go so much further than the psychological one. Indistinguishability is a negative constatation merely; it does not rule out the possibility that a distinction may exist. It may be that the distinction is simply not perceived.
The dogmatic assertion, on the other hand, speaks of the Holy Ghost making us “children of God,” and this filial relationship is indistinguishable in meaning from the uterus (sonship) or filiatio of Christ.
We can see from this how important it was that the homoousia should triumph over the homoiousia (similarity of substance); for, through the descent of the Holy Ghost, the self of man enters into a relationship of unity with the substance of God.
As ecclesiastical history shows, this conclusion is of immense danger to the Church it was, indeed, the main reason why the Church did not insist on any further elaboration of the doctrine of the Holy Ghost. Its continued development would lead, on a negative estimate, to explosive schisms, and on a positive estimate straight into psychology.
Moreover, the gifts of the Holy Ghost are somewhat mixed: not all of them are unreservedly welcome, as St. Paul has already pointed out.
Also, St. Thomas Aquinas observes that revelation is a gift of the spirit that does not stand in any clearly definable relationship to moral endowment.
The Church must reserve the right to decide what is a working of the Holy Ghost and what is not, thereby taking an exceedingly important and possibly disagreeable decision right out of the layman’s hands.
That the spirit, like the wind, “bloweth where it listeth” is something that alarmed even the Reformers.
The third as well as the first Person of the Trinity can wear the aspect of a deus absconditus, and its action, like that of fire, may be no less destructive
than beneficial when regarded from a purely human standpoint. ~Carl Jung, Psychology and Religion, Paragraphs 287-289.