The heir of the great Roman

To answer this question, imagine medieval feudal society.
In ancient slave world were the main city. They became centers of great empires. Ancient Athens was joined Greece, Rome - great power from the Danube river to the Euphrates.
But the ancient civilization died, and the town was deserted. Economic basis of life became the village and the land plot (in Latin "feud") became its center. He gave his master all. Lord have cultivated grain and grind him to his mill, baked bread in his oven. Flax and hemp turned into clothing, and skin of animals - in footwear.
Its castle of the feudal Lord consisted of stone, and economic constructions - log; both, as a rule, he found on his extensive grounds.
The only thing that he got out of the estate, is a piece of iron, and forge it was also their own. Their masters were produced nails, hoops, bolts, simple device for work in the field and in the forest.
And only luxury items - precious overseas stones and spices, honey weapons Yes handwritten books, if the owner was eager to them, acquired it at the nearest fair or itinerant merchants.
Subsistence farming feudal Lord led to the decline of trade and crafts, to the fall of culture and art, to the fragmentation of the state. Europe was like a mosaic, composed of large and small feudal estates, the owners of which almost did not depend on the rest of the world.
The unity of Europe was supported at that time religion. Only the Christian Church headed by its Supreme Lord, the Pope of Rome - was the government that recognized the feudal princes, kings, counts, barons and knights. And this advantage churchmen used very skillfully.
Christianity took leave of them with their initial ideas about the universal rejection of power, wealth, property - that attracted to this religion thousands of oppressed multinational Roman Empire. The Church itself became richer than any of the feudal Lord.
In the V century brilliant, the mighty Rome died, and with him came to an end and ancient civilization. The defeat did the rest of the tribes, the rapid flow invaded Italy.
Although Rome fell, the Christian religion that came from the depths of his Empire, has already become a powerful, centralized power. She was able to spread its influence on the leaders of the barbarians. Those were baptized and swore in her loyalty. From year to year, from century to century the power of the Church was enlarged and strengthened.
So the Christian Church was able to replace the state power of Rome, its business connections, its ideals. The Church became the spiritual successor of antiquity.
How are ordered it inherited from the ancient world?
The Church took only what corresponded to its main teachings about God and about heavenly salvation. The rest she brushed off as something sinful, can destroy the soul.
The Church refused to mind. Why do I need a reason when there is a religion? God, the only possessor of wisdom, gave people his doctrine, which has everything - science, the whole philosophy of the world, all the laws. They are written in the Holy Scriptures, and it is the duty of a Christian is to believe each line. To believe and not doubt.