Cities in Flight
Cities in Flight is an omnibus volume of the four stories James Blish wrote in this particular future history: They Shall have Stars, A Life for the Stars, Earthman, Come Home and A Clash of Cymbals / The Triumph of Time. Central to all four is two technological breakthroughs: The development of effective antiagathics (effectively turning human beings clinically immortal), and the Spindizzy drive, an antigravity mechanism and faster-than-light propulsion system that can effectively turn any large object into a functional spaceship. It is these two technologies that act as the foundation for the eponymous ﬂying cities: Entire cities have been ﬁtted with spindizzies and had their citizens turned immortal, and these then travel the spaceways looking for odd jobs to do. The four stories follow the story of human spaceflight from simple intra-system rocket travel to the ﬁnal end of the universe, with the main focus being on the star-ﬂying exploits of the spindizzy-ﬁtted New York.
The greatest strength of the cycle is the complexity and consistency of the future history itself, for which Blish has taken inspiration from Oswald Spengler's cyclic theory of history. In Spengler's view, a given cultural setting goes through a sequence of distinct phases: The early, untamed culture with novel spiritual, scientific and interpersonal insights, gradually ossifying into a highly-organized, safe and stagnant civilization, and ﬁnally declining and dying, supplanted by a new culture in its wild youth. In Blish's future history (which was conceived in the height of the McCarthyist witch hunts), Western civilization degenerates into a totalitarian police state in an attempt to defend itself against the Soviet Union, but then gets effectively conquered by the Soviet Union. Who could have thought that those guys were better at running a totalitarian police state, right? This leads to the oppressively stagnant Bureaucratic State - which, in its ruins, produces the culture of the eponymous ﬂying cities. The rise of the Okie culture (the ﬂying cities) is not even the last part of the historical cycle; many empires rise and fall in Cities in Flight, and it's easily its incredibly rich history that makes for the best reading in the series.
Its main weakness is the very uneven writing and the rather jumbled narrative - as well as the rather weak characterization (and some mildly annoying 1950s tropes). For instance, in the three main books (the ﬁrst being essentially a prequel, set much earlier), there is only one named female character. The male lead falls in love with her for apparently no other reason than the fact that she happens to be the only named female character.
The four stories themselves are four very different stories, so they get their own mini-reviews.
They Shall Have Stars
Set in 2018 (as imagined in the 1950s), this is essentially a very long exposition dump that sets the stage for the rest of the series. It deals with the invention of the anti-agathic drugs and the Spindizzy drive, seen from the perspectives of a military space pilot and a (Jupiter-based) construction worker - the latter, in my opinion, being the most compelling character in the story. Although the story itself was uncompelling and quite obviously dated (apart from the Soviet Union still being active in 2018, it also features an extinct civilization of Martians), it wasn't bad in the sense of, say, Ringworld or Sundiver, just … well, boring.
By the way, this is - for better and worse - probably the most dry exposition dump I have ever read. It even contained the mathematical formulae for explaining the Spindizzy drives.
A Life For The Stars
This one was probably the most cohesive of the bunch, and is essentially the coming-of-age story of a young farmboy who gets press-ganged into service in the city of Scranton-in-Flight, and who manages to migrate to the altogether more pleasant city of New York and attain citizenship (and, thus, immortality). It was actually a quite decent light read (I read it over the course of two bus trips), but no literary masterpiece. Quite entertaining, though.
Earthman, Come Home
Frequently considered the "main" story of the cycle, I unfortunately found it easily the weakest. It reads like a hastily cobbled-together jumble of peripherally-related short stories - which, I later found out, that it actually is. It doesn't really tell a story, per se, it's more a string of anecdotes that all happen to involve the same characters. The events connecting the mini-stories seem quite forced, and the lead character, mayor Amalfi, has entirely incomprehensible motivations for doing most of the things he does (except, of course, if he has the power of pre-intuiting what will move along the plot). Entirely forgettable.
The Triumph of Time
The ﬁnal book in the cycle felt very rushed, and quite a lot of interesting material is introduced and never really used (such as the nonhuman culture named "The Web of Hercules", which ends up feeling under-exposed more than mysterious). It deals with the end of the universe, which also happens to be the beginning event of the next universe, and how some of the denizens of New York attempt to claim control over how the next universe will develop.
The ﬁnal verdict: Ho-hum. Not bad, per se, but also not great. I don't understand why some regard it as a masterpiece.
As a rather useless aside: The Ghostbusters character Egon Spengler is, in fact, named after Oswald Spengler.