It's impossible to try to explain the entire Rork-saga. There are too many palliatives and last resorts in it, because the first two parts, Fragments and Passages were meant to be autonomous by Andreas. Only several years later Andreas picked up the thread of Rork with Le cimetière de cathédrales and succeeded to make a well constructed whole of it. Despite the palliatives and last resorts in the story, Andreas does present a vision with Rork. An vision on reality and creation.
'Rork' means token or thought, in the sense of idea, creation (Capricorne, p.24). Tokens are eventually the only thing that remains of the entire Rork-saga (Retour, p. 56). Rork is thus something universal, a universal train of thought. In any case it is immediately clear that Rork is not human. He is several hundreds years old and possesses the power to travel between several worlds through so called passages.
At the end of Retour, the last album of the series, Rork commits suicide by jumping of the skyscraper of Capricorne (p.54, pl. 1). This jump is Rork's last passage, he returns to his own world as owl.
Earlier on Rork had discovered who he really is. At first he recognizes a token on a wall in the sewers of New York, that clears the fog in his mind (Capricorne, p.36). Later in the spaceship on the South Pole all things come together when Rork looks in the mirror (Descente, p.49). The token reminds Raffington Event of two birds (Retour, p.44). "Indeed", answers Rork to this. The token thus simply represents the two owls that are waiting at the beginning and end of every Rork-album since Le cimetière de cathédrales for the return of a loved one. This loved one is Rork and eventually Rork will indeed return to the owls, to his own world.
What, then, is this world of Rork? He himself says to his friend raffington Event at page 44 of Retour: "In my world rules quietness. But sometimes the sound of large, wooden pipes awakes us... It happens seldomly and the last time it created confusion at first. A threat that was outlined against the horizon entered through your world. Now I know it was only an illusion. When the spirits had calmed down, I was taken through a passage. It was my first time, I was inexperienced. At the end of the tunnel, I was only a baby."
This explaines how Rork suddenly entered our world as a foundling (Passages, p. 10). He entered our world to stop a danger, a danger that is personified in Dahmaloch and eventually appears to be nothing more than an illusion. Pharras, (a pawn of Dahmaloch) tries more than once in vain to disable Rork. The original world of Rork is one of ideas and symbols. Significantly, the owl is the symbol of wisdom and is the meaning of Rork's name idea. Besides wisdom, the owl symbolizes death. [1) Andreas himself wrote about the owl as symbol: "I wanted to use birds in Rork and opened a birds encyclopaedia. I saw a picture of two owls and found them suitable. I was just looking for a strong image, like I found a cathedrales cemetery a strong image. In hindsight the symbolism of the owl came in very handy."] Significantly Rork returns to his world only after his suicide action.

Rork entered our world, after being awakened by the sound of large, wooden pipes. Since the era of Enlightenment we in Western Europe think everything can be explained by human ratio. This train of thought lead to a view of the earth as on ordinary lump of clay without mythical elements and without a god. At page 12 of Passages young Rork leaves this rationalistic progress-thought, by posing that there aren't as many answers as their are questions, but that there is always one question more. With this, Andreas makes clear in one sentence in what kind of a world Rork has landed. Rork lives in a cosmological world, one in which human reasoning hasn't demythologized life.

Rorks world is filled with mystery and unearthly matters. Thus the human race appears in Fragments to be not the only intelligent race on this earth [2) This horror-element originates with H.P. Lovecraft Lovecraft, an American writer that had a great influence on Andreas. This horror-author outlines in his 'Chtulhu'-saga a higher intelligence, that lived on this earth before man did. Just like in Rork the creatures awake to regain their place. By the way, this motive we find in Andreas' Cromwell Stone as well] and do some people possess supernatural gifts.

Further, the people in Rork never get a grip on the world around them. There are higher intelligences and forces of nature against which they are worsted. Thus, the remedy against the stain in Fragments appears insufficiently fit to stand against the power of this being and are the scientists in Descente unable to cope with the intelligence of the alien spaceship.
At first Rork is fascinated by the world in which he found himself. This changes after he has found his true nature. In his last words to his dying lady friend Low Valley he says: "In what kind of world are we living, that bleeds and dies the moment it comes in contact with reality?! Let's hope, Low, that the dreamer doesn't dream forever! That he wakes up one day and sees things as they are and not as he wants to dream them, under the pretence that life is what he wants, not what he is! All we do here is mere cheap mysticism..." (Retour, p. 45)
Rork knows that man doesn't live in reality but in a self-made reality. Thus everything appears to be nothing more than mysticism, an illusion. At page 53 of Retour he confronts the illusion of evil, Dahmaloch. "I can see now that everything depends on me," says Rork. "From my resistence against your machinations You have drawn strength and energy. But things turned out different from what you expected and now You hope to satisfy Your ambitions through a duel. If I accept, I only strengthen the famous ideas of devil and hell. Man was not created for chaos or perfection. The reason for his existence is the road that leads from one thing to the next. Only his attempts give him the strength to live. If he succeeds, this is the end of the world. Whoever you are, You nearly made it. Nearly. Well, Your accomplices have killed themselves... You can do the same thing yourself."
Following this Rork kills himself by jumping of the skyscraper. Dahmaloch is eaten by the ferryman. With the denial of the idea Dahmaloch, the Dahmaloch evil has disappeared as well.

What then is Andreas' message? Man doesn't understand his world. This much is clear. Not only does Rork say this in his last words to Low Valley, he has also - by saying that their is always an unanswered question - pointed out in Passages that life is inexplicable.

Andreas' message is a philosophic one, comparable to the German philosopher Arthur Schopenhauer (1788- 1860). According to this thinker the world consists of two layers: that of will and representation. The world of will is the true world, that underlies every idea man suggests about what this true world really is. Every representation of life creates its own reality. The will is within ourselves and is inexplicable, it is the urge that leads us from one thing to the next. Man nevertheless seeks desperately for an explanation for that will. He forms ideas of religion (Le cimetière de cathédrales), gods of nature (Lumière d'étoile), fate (the astrology of 'Capricorne') or a extraterrestrial power (the spaceship in Descente). All these ideas are only cheap mysticism. The more so because the reality that is created by such an idea starts to live a life of its own. Eventually Rork sees that evil, personified in Dahmaloch, can only exist because man forms an idea about it. By realizing this Rork eventually saves the world.

"Returning again You are eternal," Dahmaloch says finally at the end of the last page of Rork. "And the dreamer that dreams. Always prepared to dream. Who should want to wake up. Hm? Who?" With this he summerizes Andreas' message: man is a limited creature in an almighty universe on which he has no grip. The only way to keep himself up, is by forming his (simplified) realities. He does this though the dream, though the idea, through the creation like Rork...