In our last episode, a European Universal State is founded sometime around the first quarter of the 21st century: a momentous event that we pass over in discreet silence, so that our future history won't become outdated soon enough to embarrass us.
Toynbee thought that all the world's other civilizations were already dead in the ditch; thus the West's universal state would be truly universal (at least if your Universe is Earth). Other civilizations have since given hints that he held the coroner's inquest prematurely. Europe as merely one contending Earth-based power sounds more like the 19th century colonial scramble than the grandeur that was Rome, but if Toynbee could be stretchy with his history so can we. We'll let the full-blown Terran Empire - or should it be l'empire terrestrienne? - emerge in its full glory only gradually.
According to Toynbee our Western universal state should last 400 years, give or take, to sometime around 2420. That's not such a bad date for the Fall of the Terran Empire, is it? Worth scrambling back to the 17th century for an anchor point. Four hundred years seems like just about time enough to invent starships, find planets, colonize them, and create an interstellar empire. Then to party so hearty in celebration that when you come to on the floor the Empire has collapsed and space vikings are running around getting their horned space helmets stuck in airlocks.*
Toynbee also helps us fill in our chronology. The empire will hit a rough patch about 200 years before the end, long around 2218 or so. We can shoehorn in the American Revolution in Space here; why not? It must sort of fizzle out, though - Old Europe failing to learn from the Noble Colonists - since the empire picks itself back up and keeps going till it falls for good in the 25th century.
Other stuff will happen as well, according to Toynbee. One or more new great world religions will be founded (we may hope this was not a prediction of Scientology). As to why the empire will fall, considering that he wrote ten volumes on the subject, Toynbee is surprisingly hazy. It isn't just the old standby, becoming decadent and hedonistic - Toynbee knew perfectly well that the really wild parties, Petronius the Arbiter and all that, came in the early days of Roman Empire, not its last days. The whole thing just sort of runs down.
Its' easier to imagine why the Terran Empire would fall: by tripping over its own enormous scale. A truly cosmic real estate boom - sunny quarter-acres on Gleise 581c! - would naturally produce an equally cosmic bubble and bust.
Once I built a world, now it's done;
brother, can you spare a dime?
A civilization that needs an FDR gets some well-meanng bureaucrats in Brussels - if that isn't enough to bring down the Terran Empire, what is?
Toynbee schedules some aftermath, too. A proper Interregnum lasts some 300 years - which gets us up to 2720 or thereabouts - and may feature one last college try at restoring the empire, sort of like Justinian and Belisarius, maybe around the late 2500s. It goes flat, but by 2720 the worlds are stirring, trade is growing - all that stuff that calls out to true geeks to find their RPG rules and 20-sided dice. It's Civilization Time!
In the end, as it turns out, we haven't gotten all that much from Toynbee, which probably explains why he has fallen down the memory hole. He never does quite tell us why our Terran Empire falls; we had to conjure up that for ourselves. Hari Seldon he wasn't. All we got was a bare timetable, but for the creator of a long-scale future history it's something - "2421: date traditionally given for the fall of the Terran Empire ..."
* Yes, I know - the original Vikings didn't run around wearing horned helmets, either. They did have cool dragon ships, though.