For Your "Mutability of Empires" File

Two items. the first comparing Britain and its Imperial vassal, India:

In the beginning, there were two nations. One was a vast, mighty and magnificent empire, brilliantly organized and culturally unified, which dominated a massive swath of the earth. The other was an undeveloped, semifeudal realm, riven by religious factionalism and barely able to feed its illiterate, diseased and stinking masses. The first nation was India. The second was England.

--Alex von Tunzelmann, Indian Summer 13 (2007)

And two, Froomkin's Corrolary:

Every empire attempts to expand until it can occupy Afghanistan. Those empires which cannot so expand are replaced by ones which can.