The Church guided scientific progress and preserved the learning of Greece and Rome and continuted their studies. St. Isidore of Seville, for example, has been largely ignored in the English speaking world despite convincing the barbarian tribes to preserve Roman libraries and even developing a precursor to the database in order to catalogue that learning. St. Isidore also solidified a version of classical education based on the Trivium. Add to the list guys like St. Albert the Great and dozens like him, and there certainly were advances made after the fall of Rome, but it is almost always catastrophic when an empire that size collapses. The "Dark Ages" was generally used by post-"Enlightenment" thinkers to denigrate the Church, and is generally a myth. The people of the Middle Ages were not consumed by Scientism as we are today, and were almost definitely happier in their day to day existence than we are with all of our so-called advances, but the Renaissance would never have happened without the Middle Ages. Personally, I would be happy to trade in everything invented after the Industrial era to return to an existence where your town or village was your family in a high trust society.