It was also one of the main factors Edward Gibbon blamed in The History of the Decline and Fall of the Roman Empire. However he had a somewhat different mechanism in mind than lionhearted's comment: he argued that Romans, as they got wealthy, no longer wished to personally serve in the military, so they hired mercenaries instead, which had the three effects of reducing the military readiness of normal Romans, filling the army with less loyal foreigners, and increasing the tax burden on agriculture. (It's worth noting that there's a lot of debate among later historians over whether that's the correct analysis.)

> Oswald Spengler made a similar argument in 1918

Not really, his main argument was that the western society has lost control of its technology. We (the west) are like a horse carriage where the driver has been thrown of and the horses (technology) are driving the carriage (us) in a wild ride towards the cliff. [An updated version of this philosophical thinking is Bill Joy's Grey Goo article "Why the future doesn't need us." http://www.wired.com/wired/archive/8.04/joy_pr.html]