In what follows I will try to describe what was new and distinctive about Tolkien's writing - the X-factor that makes Tolkien's myths more and more interesting and relevant, even as 'traditional myths' dwindle in perceived relevance and power. I will try to explain how it is that Tolkien achieved the apparently-impossible: the making of new, yet real, myths - myths for now and the future, as contrasted with myths from the past.
From the middle of the twentieth century, the most dominant explanation for the power of traditional myths was that of CG Jung; which was amplified and popularized by Joseph Campbell.
This idea is that myths have their psychological power because they tap-into the collective unconscious, where there exist universal archetypal symbols - such as characters and plots - that are found (with only superficial variations) in the myths, all Men's dreams, the psychotic phenomena of the insane, and the visions of trance-medium spiritual experts such as shamans.
In other words, the power of myth is supposed to be a function of its roots in the unconscious, and this collective unconscious is universal - but manifested in the 'folk mythologies' that arise in particular cultures - and are especially evident by comparing tribal or ancient societies (where they are assumed to emerge, and where there is less possibility of cross-cultural transmission).
By this account - a myth symbolizes the unconscious and puts in touch with 'the universal'.
Ever since the 1960s there have been many attempts to explain the power of Tolkien's work in these broadly-Jungian terms - for instance listing his sources in Norse or Celtic mythologies.
Obviously, there are such connections and influences; yet I am sure they cannot be the main reason for the special power of Tolkien's work - because it is obvious that for many people Tolkien's work has more power and truth than the myths from-which he is supposed to derive them.
Likewise descriptions of the supposed archetypes (such as the wise old magician, of whom Gandalf is supposed to be a version) are interesting - but lack the particular power of the Tolkien manifestation.
Likewise the supposed plot archetypes such as the hero quest. Tolkien's actual quests in The Hobbit and Lord of the Rings have some resemblances to these; but also differences. And although Tolkien's quests come later, they have a power that is experienced as deeper than the supposed originals.
Owen Barfield, who was a friend of Tolkien but who did not enjoy (and could not finish reading!) The Lord of the Rings; provided what I regard as the basis of a deeper and more historically-explanatory understanding of myth.
Barfield's scheme would see myth as originating in the immersive, spontaneous and unconscious way of thinking - the 'mythic consciousness' - of ancient tribal Men (and young children as well, albeit within their lesser cognitive abilities).
Originally, it would be supposed, this consciousness was Not found as separate 'myths' as we now recognize them, but as simply the whole way of life and being - in other words, consciousness was itself mythic, and there was no need or function for special myths.
The stories we recognize as myths come from the later stage when adult Men begin progressively to lose this spontaneous and natural consciousness. Such Men no longer lived immersed-in the mythic; and therefore access to the 'original' form of consciousness could only be attained intermittently and by using methods - such as inducing visions, or by song, story, ritual, artifacts and symbols - by religious and magical practices.
In other words; as mythic consciousness began to wane, myths began to emerge.
Myths were meant to be true; deeply true; and with a truth that was deeper than ordinary everyday facts and information. True beyond words and explanations.
I would say that, implicitly, myths were a means to an end - and that end was the return to original mythic consciousness.
But as the original mythic-consciousness continued to wane throughout human history; matters reached a point where mythic consciousness could only be accessed or activated temporarily. This by means of mythic stories, for example - and usually within some kind of 'ritual context' which spiritually-prepared the participants.
(I am thinking of - for instance - myths as performed by someone gifted such as a bard, in a solemn and focused public situation.)
Then, as the process of waning continued - Men's normal, mundane, everyday consciousness could no longer experience myth. To contact and experience mythic consciousness context required inducing some degree of altered consciousness - at the least a 'light trance' state; which might be induced by music, rhythm, chanting, dance or even physical interventions such as fasting, or sleepless vigils.
At the extreme, and especially in the late-19th and early 20th century - writers and other artists tried to eliminate choice and awareness, aiming to 'allow' the unconscious to well-up into direct expression.
Deep meditation training, surrealism, automatic writing, trance mediumship, clairvoyance, consciousness-altering drugs...
All such techniques are based on the underlying idea that the artist's 'self' or ego' needs to, ought to, step-aside and 'allow' the collective unconsciousness to well-up into consciousness - the artist merely functions as a scribe for the resulting spontaneously-generated material.
But the resulting mythic experience was not just temporary, but the necessarily-altered conscious state also tends to make mythic experience separate from 'normal' (non-mythic) life; and to impair memory. And the very extremity of methods tended to invalidate the mythic experiences - which could easily be written-off as merely pathological.
And with further development and waning; even the possibility of even extreme measures to enable a renewal of contact with mythic consciousness all-but disappeared - and we entered the characteristic modern state of pervasive, shallow, mundane materialistic thinking.
When we have reached the modern era (that is, from the later 20th century), there has been an almost-complete separation of everyday- from mythic-consciousness.
Separation of the mundane and the mythic even to the extent that the apparatus of traditional myth has lost power and become of dwindling popular interest; and the spectrum of methods, techniques, rituals and symbols have all-but ceased to evoke mythic consciousness.
And yet - this does Not apply to the works of JRR Tolkien - which seem to go from strength to strength.
So what is the difference?
My best guess is that Tolkien was not writing myth - he was not even trying to write 'a myth'. His work therefore does not operate by awakening, or evoking resonances of, un-conscious mythic consciousness.
So if not working with myth - then what was Tolkien doing? He tells us himself.
Tolkien was, I think, aware that he was doing something different and relatively new with his writing; which is why (in the essay On Fairy Stories) he invented the term 'subcreation'.
Tolkien's creative process was much more conscious, deliberate, and freely chosen than earlier myths - Tolkien was deliberately creating in a smaller version of divine divine creation; instead of - like myth - inducing contact with already-existent divine creation.
In essence; I would say that Tolkien wrote in that higher form of 'after-modern' consciousness which Barfield termed Final Participation, and I have called primary thinking.
Because primary thinking is the medium of subcreation, it can happen only when the artist's thinking is aligned with divine creation - when the artist's creation harmoniously adds-to divine creation.
Under such conditions the artist's creativity is an expression (a translation) of the artist's real and divine self - rather than his public persona, his everyday personality and socialized self.
But Men cannot (in this earthly mortal life) continuously or for long periods attain to this level of divine-aligned and subcreative consciousness - therefore the composition process often requires a great deal of trial and error.
That is - repeated trials of composing a mixture of genuinely inspired and erroneous material, and then later testing what has been composed against the artist's intuitive sense of rightness and truth (elimination of error). This is a process we can observe at work in those exploratory drafts and re-drafts published by Christopher Tolkien as as The History of Middle Earth.
What was Tolkien testing his compositions against? One possible answer would be 'the collective unconscious' in some form or another. And this must have some truth - new myth needs to have some kind of consistency-with ancient myth.
Yet this is not, it cannot be, the whole story; nor even its most important elements - because this would be only secondary-creation, re-creation - but not sub-creation.
If Tolkien was only evaluating on the basis of back-compatibility with ancient myths, this would lead merely to variations on perennial themes. It could not explain why Tolkien's writing has 'bucked the trend' of declining power in myths; has become more, rather than less, powerful with passing decades.
Likewise, Tolkien's much discussed rigour in ensuring coherence throughout his invented world; ensuring that every aspect linked-across to the others - to make his world as internally-consistent as possible.
Inner-consistency might explain certain aspects of depth in Tolkien's world and an aspect of realism; but there must be more.
Because inner-consistency does not explain the mythic sense of vital relevance to our lives of Tolkien's best works; their purposes, motivations and meanings which are experienced as far deeper and more-real than everyday modern existence.
After all, an internally-consistent and complex invented world would merely be experienced as an intricate and ingenious toy - unless is was also something deeper and more personally important.
I regard what is most special about Tolkien's creativity - its X-factor, if you like! - as something genuinely new, truly generative, and originative.
I infer that therefore Tolkien was actually testing the validity of his subcreated written compositions against ongoing divine creation. But not just in terms of back-compatibility - but in terms of present and future divine creation.
In other words; when Tolkien was writing at his best, I think we should regard him doing so in a higher state of consciousness that was aligned with divine creation: that was indeed in accordance with God's creative purposes.
Therefore his testing and revisions were in effect comparing what was written with Tolkien's living understanding of God's ongoing creative goals and methods: future as well as past.
This state of consciousness in which I believe Tolkien composed should, I believe, be envisaged as highly aware - including self-aware; as expansive and wide-ranging. It was, indeed, the kind of thinking when thinking is itself reality; in which thinking is simultaneously aware-of existing reality, and making-of new reality. And that is 'the secret' of JRR Tolkien's writing; what sets it apart from almost everything else.