Brian Aldiss: Helliconia: How and Why (you might want to enlarge the typeface)
For many years I had contemplated writing a story about a world where seasons were so long that all one's life might pass in spring, say, or in the winter.
...
It was clear from the start that I would need advice for all the disciplines needed to fortify the narrative: history, biology, philology, and so forth. At the basis of everything, the astronomical and geophysical aspects - the details of the Helliconian binary system - had to be as correct and current as could be. Today's theories were wanted, not yesterday's.
So I consulted the various authorities whose names are acknowledged in the novels. Most of them entered into the game of Helliconia readily, and had fruitful suggestions to make. Most specifically, it was Iain Nicholson's description of the binary system and how it came about which opened up what I regard as one of the most profound themes of the novel, the process of enantiodromia, by which things constantly turn in to their opposites; knowledge becomes by turns a blessing and a curse, as does religion; captivity and freedom interchange roles; phagors become by turns conquerors and slaves. As a means of making concrete this amorphous but deeply felt theme, the binary model was ideal.
Phagors:
Helliconia is presented as a strange and wonderful planet. So it is. But so is Earth, and there is little that happens on Helliconia which has not happened in one form or another on Earth. The one major difference is the existence on Helliconia of other intelligent or semi-intelligent species: most notably the phagors, that ancipital race perpetually warring with humanity for possession of the globe.
Although deadly enemies, phagors and humans exist in a commensal relationship with each other. Much of the story is taken up with this painful relationship, which must be broken and yet would be fatal to break. On Earth we have no phagors, only the animal sides of our natures, with which we are similarly at war, and with which we must come to some kind of agreement. This problem, exciting as any encounter with a mounted phagor, finds explicit place in the final volume.
These are amazing books. Anti-fantasies yet genuinely strange. I want to revisit that universe again and it's only been about three years. (Avoided them initially because they coincided with the early-'80s trend of inventing a fantasy world and milking it over several books, which is what still keeps "science fiction" alive in the market. Aldiss obliquely acknowledges that pressure but makes the sincere case that this is a single massive novel split into three parts).
One disturbing factoid from the same website: Aldiss' great first novel Non-Stop was never filmed because, Aldiss says, a Kubrick subsidiary bought the rights to anything that might challenge 2001 in the market. The purpose was to bury the book. If true*, Kubrick's narcissism was beyond the pale--the abuse of intellectual property rights by the movie business taken to another level of ego.
* And it seems likely since Aldiss later spent much time in Kubrick's presence developing what eventually became the dreadful AI.