Heather goes on to argue that the main pressure on the Roman frontier in the 3rd and 4th centuries came from the Sasanid Empire in Persia, which he calls a second superpower of the ancient world. A series of defeats at the hands of the Sasanids in the 3rd century pushed Roman emperors to reform the army and increase its size by at least a third. They needed to raise taxes to pay for a larger army, and they also expanded central administration to better manage the increased revenue.
Heather moves on to a discussion of Roman ideology concerning barbarians, introduced by a few anecdotes concerning the Romans relish for slaughtering them. A remark by the 4th century Roman orator Themistius leads in to what Heather sees as the key Roman view about barbarians -- that they were completely driven by desire, and thus irrational. Civilized Romans, on the other hand, were supposed to exercise rational control of their desires. This led Roman intellectuals to view their society as totally distinct from and superior to the barbarians, and even divinely favored.
The earlier anecdotes, however, suggest that loathing for barbarians was a mass phenomenon, too, and that in fact seems a requirement of mobilizing the resources of Roman society to resist barbarian incursions. But Heather's discussion of ideology doesn't explain how this popular disdain was was generated -- I wouldn't expect that the elitist ideology could simply carry over, since in some way it was also involved in justifying elite rule over common Romans.
This expectation of total superiority over the barbarians created difficulties for official propaganda, however, since the results of conflicts were often not so clear cut (or even favorable at all). Heather returns to Themistius throughout the chapter to show the problems he had providing the official spin on a number of different encounters with barbarian adversaries.
Heather brings up Athanaric, the Gothic chief, and Ulfilas, the Gothic Christian religious leader, to demonstrate that the Gothic world was not, in fact, sharply divided from the Roman one. Athanaric understood the Romans well enough to play off factions against one another in attempt to improve the conditions of his relationship with Rome. Ulfilas, a Gothic Christian leader who was actually the son of Roman captives, weighed in on the controversies besetting Christian doctrine as it was officially specified in the Nicene era.
Heather extends his discussion of Roman-barbarian interdependence with a discussion of the alternating aggression and clientage of Germanic kingdoms along the Roman border in the late imperial era. He takes this high degree of interdependence as a jumping off point into a discussion the revolutionary changes in barbarian society.
Heather notes that the Germanic tribal names appearing in Roman texts both changed and diminished in number in the 3rd and 4th centuries. He cites this as evidence of political consolidation. He uses the archaeological findings from German settlements and industrial sites to argue that German agricultural and economic production exploded from the 1st to the 4th century. He adduces archaeological evidence of increasing stratification in burials to argue that Germanic society was becoming similarly stratified. He takes the evidence of large-scale consumption at palace centers to show that political leaders were able to support increasingly large retinues, and he suggests that the power conferred by large collections of armed followers would explain the ability to consolidate larger political units and extract a larger proportion of the economic surplus for a social and political elite. Heather believes that Germanic society was still far short of feudal society in its stratification, however, because even the legal documents from the successor kingdoms show the existence of a very significant class of freemen.