Now just take a look at those books there. 8 volumes by David Wingrove making up his Chung Kuo series. All those paperbacks are UK first editions, so you'd think they might all look somewhat similar. But no, someone from the publisher's marketing department decided to change the design twice during the initial publication of the series so I get a mixed looking shelf.
While that is slightly annoying to the pedants out there I'm more concerned about what goes between the covers than what's on them. Not in the case of this series actually (it just made a nice picture to illustrate the point) but of fantasy and science fiction series in general.
When watching a tv series you kind of expect things to alter between episodes as there are generally a whole raft of writers each tackling their own episodes. They all get written in parallel without the benefit of seeing what has come before so mistakes slip in. What bugs me though is when things change between books in a series with only one author.
I'm not just talking minor changes either - the odd spelling change to a character name I can forgive - but wholescale re-writing of history. I'm currently listening to Terry Brooks' Shanarra series and there are numerous examples where he changed the history of the four lands in writing the prequel - which was the eighth book to come out. Fandom has the name Retroactive Continuity for this and I'm not keen on the concept. If you've established a coherent world I do think you should stick with it no matter where in that world's timeline you are working. OK, so it may mean having to reign in some of the wilder imaginings but at then the author also has the challenge of keeping the suspension of disbelief going.
I'll talk about another pet hate of mine in fantasy literature another time (not one that stops me readingit though!)...