adams proceeds from rome to the middle ages, in which nomadic barbarians (mostly of germanic origin) spread throughout the empire, eventually settling and establishing kingdoms in gaul, iberia and italy. as it might have been predicted, these small kingdoms were soon at war with each other. initially, these kingdoms, unlike the empire, were able to support themselves. the cost was a loss of technology, and a temporary lapse of high civilization during what has come to be known as the "dark ages". christianity, still headquartered in rome, gained much in prestige during this time, and came to wield enormous power. the church amassed huge amounts of wealth through various means, fair and foul. by 1200 ad, the pope had far more power than any secular ruler. overall, the middle ages were a period of decentralization where people were bound together by oaths of loyalty (feudalism and manorialism), rather than national identities. superstition and the "imaginative mind" gained preeminence, along with religious fervor. by 1095, the beginnings of europe's modern nation-states could be discerned; controlled, often not willingly, by the catholic church. "until, the mechanical arts have advanced far enough to cause the attack in war to predominate over the defence, centralization cannot begin…" the first crusade represents the point at which western europe took its first steps toward centralization. europe was thoroughly self-sufficient, yet stagnation was not far off, and an infusion of capital was needed. perhaps no-one thought of it in those terms, but there was a sense that european influence should expand, and the reconquest of jerusalem was a good cause to inspire the necessary fervor. the "opening" of the holy land is significant to western culture for three reasons: economic capital, cultural renaissance, and trade. when the four crusader kingdoms were set up following the sack of jerusalem in ad 1099, large amounts of wealth were discovered and sent back to europe. this cured the immediate fiscal problems. also, the greek and roman classics (which had been preserved by arab scholars) were rediscovered, which led to an increased interest in antiquity. finally, and most importantly, trade was resumed between the east and the west. this allowed new imports (such as silk and spices), and a new market for european exports. the economic push provided by the crusades encouraged centralization, but also fueled tension between church and the local governments. if the monarchs of europe wanted increased power and wealth, they would have to take it from the catholic church. the monasteries proved to be an immediate source for much of the wealth. their vow of poverty prevented the monks from using most of their money; consequently, monasteries and churches often contained great hoards of tangible wealth. the coming of the reformation proved disastrous for them, as secular monarchs were emboldened to intimidate, coerce or abolish them to obtain their wealth. this redistribution eventually led to the secular monarchies gaining predominance over the holy see.