Background: The Fall of Rome
The Roman Empire collapsed as a political entity in several stages during the 5th, 6th, and 7th century CE. Specifically, these are:
- the crossing of the Rhine by the Germanic tribes that could not be repelled in 406
- the abandonment of Britannia shortly after 410 CE
- the collapse of the defense of the Empire in Italy against Alaric's band of warriors (that would later form the Visigoths) and the subsequent sack of Rome in 410 CE
- the takeover of various parts of the Western section of the empire by the Visigoths (Western Gaul and Iberia 413), the Vandals (Iberia 409, Nort Africa 429), the Suebi (Iberia 409), the Burgundians (Eastern Gaul 411), the Ostrogoths (Italy 489) and the consequent loss of territorial cohesion of the Western part of the empire.
- the takeover of the Italian heart of the empire by Germanic mercenaries (gradually from the incident in 410, formally in 476, when the last Western Roman emperor was deposed(*)). Notably, the Eastern Roman emperor nominally still retained suzerainty over the entire Empire. There were also still remnant provinces (e.g. Soissons and Mauretania) deep inside Western Roman territory that were still governed by Roman officials, though they were probably not in contact with the Roman emperor (the remaining Eastern Roman one).
- the destruction of the Roman navy by the Vandals (notably the Eastern Roman one in the Battle of Cap Bon in 468, but they did, of course, also destroy the Western Roman fleet)
- the inability of Justinian's the Eastern Roman army to secure the reconquered Italy (535-572). Given that this was the symbolic and historic heart of the Empire as well as the seat of the pope, this is kind of a big deal.
- the collapse of the defense of the Empire in the East and the occupation of Egypt by Khosrow II in 618
- the utter inability of the resist the attack of the caliphate in the 7th century in Northern Africa, the Levant, and, subsequently, the Mediterranean islands (Egypt being taken by an army that was only 4000 strong)
- the loss of the Roman political institutions (The consulship being allowed to lapse in the early 500s. Other republican and military titles (dux, judex, Caesar, comes, etc. etc.) transformed into feudal nobility titles. The institution of the emperor transformed from a (nominal) princeps of the republic in the tradition of Caesar and Augustus to that of a god-given kingdom (and actually styled himself βασιλεύς, king, not imperator or αὐτοκράτωρ as before).
- the demise of the Roman civil administration, especially in Italy due to years of chaos in the early Langobard era, and elsewhere.
- the collapse of the economy, the infrastructure, the population, urban areas (the city of Rome's population declined from a million to a few thousands), etc. (For more data than in the Wikipedia pages, see Ward-Perkins' 2006 book The Fall of Rome and the End of Civilization)
- the end of the Pax Romana
Some of these events were more symbolic and though politically relevant had little bearing on the lives of ordinary people. However, the collapse of the economy, the infrastructure, the decline of the population, etc. must have been felt and must have had terrible consequences for everyone. This is documented to some detail in Ward-Perkins' 2006 book The Fall of Rome and the End of Civilization.
Question: What did the Romans think about this?
Although the process, stretching across more than 2 centuries, was slow, it must have been evident to most contemporaries. So: What did they think about this? To what extent did they anticipate this? Do we have sources attesting to that? (Note that these questions are so closely interconnected that it does not make sense to open separate questions here on history.SE.)
What I found so far
Unfortunately, I found very little about this so far. One example is apparently Paulus Orosius writing about the sack of Rome in 410 as described by Ward-Perkins (2006 book The Fall of Rome and the End of Civilization):
The Christian apologist Orosius, for instance, wrote a History against the Pagans in 417-418, in which he set himself the unenviable task of proving that, despite the disasters of the early fifth century, the pagan past had actually been worse than the troubled Christian present. In describing the Gothic sack of Rome in 410, Orosius did not wholly deny its unpleasantness (which he attributed to the wrath of God on Rome’s sinful inhabitants). But he also dwelt at length on the respect shown by the Goths for the Christian shrines and saints of the city; and he claimed that the events of 410 were not as bad as two disasters that had occurred during pagan times—the sack of Rome by the Gauls in 390 BC, and the burning and despoiling of the city under the Nero.
Ward-Perkins is not actually primarily interested in how Romans perceived their impending decline, but in showing that the fall of the empire was actually bad in economic terms, accompanied by a collapse of wealth, of population size, and of the technology level.
Orosius' own account (History against the Pagans, book VII.39 and following) takes the attitude to propose that everything is not as bad as it looks and that whatever bad things occur do so as the instrument of the just and understandable wrath of god. In his own words:
For how does it harm a Christian who is longing for eternal life to be withdrawn from this world at any time or by any means? On the other hand, what gain is it to a pagan who, though living among Christians, is hardened against faith, if he drag out his days a little longer, since he whose conversion is hopeless is destined at last to die? (Orosius, History against the Pagans, book VII.41)
In view of these things I am ready to allow Christian times to be blamed as much as you please, if you can only point to any equally fortunate period from the foundation of the world to the present day. My description, I think, has shown not more by words than by my guiding finger, that countless wars have been stilled, many usurpers destroyed, and the most savage tribes checked, confined, incorporated, or annihilated with little bloodshed, no real struggle, and almost without loss. It remains for our detractors to repent of their endeavors, to blush on seeing the truth, and to believe, to fear, to love, and to follow the one true God, Who can do all things and all of Whose acts (even those that they have thought evil) they have found to be good (Orosius, History against the Pagans, book VII.43).
In the second quote, Orosius ominously insinuates that one might think that all this misfortune is happening in response to the recent conversion to Christianity. The empire had gradually become a Christian state over the century leading up to the sack of the city. He does not mention or cite anyone who actually made that argument, but his addressing it might indicate that there are writers that do. Or alternatively, that it was at least conceivable to ancient Romans of that time (and a good bit more logical than his own interpretation). It also indicates that he was aware of a decline of civilization of some sort unfolding around him, although he was determined to ignore and deny it.
(*) Kind of. The previously deposed Western Roman emperor Julius Nepos was stil around until 480.