When was Rome doomed?

[Uticensis]

Among the more interesting theories that I have heard for the end of the empire was the massive increase in the number of men becoming monks, leading to decline in population etc. This theory is based on the fact that at one point apparently one third of all men in Egypt had got the weird haircut and all that went with it. Not sure how much I believe it however...

Yeah, that's a pretty old-fashioned theory. It is part of Edward Gibbon's explanation of why Rome fell (the loss of manpower was part of the "triumph of religion and barbarism" that he said brought down the Empire). Hardly any serious historian puts much emphasis on that anymore. The amount of manpower that went into the Church was only a drop in the bucket. And, anyway, the Church took over some functions of the state, starting in the time of Constantine and expanding more and more over time, so I think things evened out in the end.

One thing to note is the Roman "virtue" of looking back in awe of their superior ancestors. This to me is a sure sign of a society in decline. Roman authors

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almost

unanimously look back at (for them) historical times as better than where they were currently living at. This is not a healthy habit, especially as it was often not true. Debate exists over the reasons for this attitude, whether it was simply guilt, or far more complex feelings in regard to the fact their societal ancestors had conquered the world while they lived comparatively easy lives. Many Romans even idealised the lives of the "savages" they conquered, living much closer to the land and avoiding the corrupting influences of power and money.

This was common in the Greco-Roman world. The people in the past were always thought to be better. This goes all the way back to early Greece: the ancestors were out with Achilles doing heroic deeds, killing crazy numbers of Trojans, blah, blah, blah. Whether its a healthy habit or not, I think all cultures do this to some extent.

I don't think this has anything to do with Rome's fall. Indeed, I don't think we should look at the fall of Rome as the people becoming weak or decadent. That's a very Victorian mindset. In all times, there a smart and stupid people, and strong and weak people. I think it is better to look at the fall of Rome as the failure of a very complex machine.