History teaches many things. Prominently, we might say that it teaches us that nations rise and fall. When nations fall, the prime cause, if indeed causes do exist in these realms, is not external conquest but internal corruption. We may object saying that we clearly see nations conquered by other nations, so surely this is ‘proof positive’ that nations do fall due to external conquest. I would respond that it is due to the very nature of internal corruption that external conquest becomes possible. This is of course a generalisation, but I think it one worth clinging to. The process…