“It was the first time in the history of Rome that its leadership willingly ceded the chance to expand and take more territory, to refuse to make the investment of coin and solider and prestige needed to keep growing to the natural borders of the ocean…”

Is not true on a number of levels, the most obvious of which is that the Romans had tried and failed to push their frontier in Europe to the Elbe more than 100 years earlier. And of course there is the troubling notion that Hadrian’s Wall represented the beginning of the end of Rome, when in fact the Empire would tool along in the West for another 300+ years after it was built.

The boring truth is that the borders of the Roman Empire at its height almost everywhere corresponded more or less to the frontiers of the land on which agriculture was possible during that era. (The exception was in the east, where the border was with another organized empire, not random barbarians.) The Romans were good at controlling and taxing settled communities and farmers, and not good at controlling and taxing nomads and semi-nomads. They tried to get around this in Scotland because they thought, hey, this place is an island, would it be that hard to conquer even the nomad-y bits? Turned out it was — they sent armies up there but there was no towns or kingdoms or whatever that they could “conquer” in the sense that they were used to conquering people — so they figured, hey, you know, this border is actually pretty short, how ’bout we just build a wall instead.

The profit margins expected in publishing are, literally, laughable to almost any other industry, some of whom are happy with 5 percent — and still manage to run a profitable business.

Guess it depends how you define “profitable.”