The Western Roman Empire collapsed more than 1500 years ago, while the Eastern Roman Empire survived for almost a thousand more years. When the west collapsed, no one questioned why. It was simply the way things were. Than about 500 years ago scholars begin to question just why the west should fail and the east survive. A long list of reasons have been presented, but they are seen as contributors to the fall, and were not the primary cause.
The Roman Empire was a military nation that was built by the sword. She was also a nation with many internal conflicts. There is a tendency to examine Roman history from the sword, the turmoil, and the many internal conflicts, but Rome was also an agricultural nation built by the plow and the sickle. When we take a close look at just how agriculture was managed, or in many cases mismanaged, it becomes all to obvious why the Western Roman Empire collapsed so quickly, and why the Eastern Roman Empire endured for a millennium.