The Medieval Era
Constantine's conversion to Christianity and subsequent Edict of Milan in 313 AD formally indicated the arrival of religion in the world of the Romans. Stoicism had been the quintessentially Roman philosophy, and it had became ever more relevant to people who saw their freedom slipping away with little they could realistically do about it. "Why worry? Accept the dictates of fate" seems to have been Roman culture's answer to the crisis of Empire. Christianity was so successful among the Romans because it so neatly put a religious wrapper around stoic ideas, allowing it and the many Stoics to be absorbed into Christianity.
While the church did not see learning in a very positive light, the Romans had already turned their backs on learning for learning's sake, which was essentially a Greek passion. It is no coincidence that the Renaissance Italians, who were mourning the loss of learning, studied at the feet of the Greek scholars who had fled the fall of Constantinople in 1453 AD. The Greeks had never lost learning in the East the way it had disappeared in Western Europe; in fact this was history repeating itself, for the Romans had learned most of what they knew at the feet of Greek prisoners and slaves who were brought back from the Roman campaigns in Greece circa 200 BC. The Germanic barbarians and / or the Christian church were not responsible for the ways in which certain kinds of learning were devalued, nor was it even a Medieval Era phenomenon but had its roots in Ancient Era Roman society.
Moreover, it was only in specific areas that the Medieval Era saw a decline in learning. The liberal arts were largely decimated. Rhetoric, math, astronomy, history, reading, and writing had once made up the core of a Roman education (and merely the beginning of a Greek education). All these studies were largely set aside for the more important business of battle, religion, and politics. Books declined in importance. However, it should be noted that here too, the problem was largely one begun by the Romans. During the Ancient Era, education was not especially widespread. Only with the advent of Greek democracy and the Roman Republic did it become truly important for a large proportion of society to receive an extensive education including full literacy. When the Republic was set aside by the Roman emperors, only the bureaucracy required such an education and it was already in full retreat by 313 AD. However, these were true liabilities for Medieval Europe.
However, the practical studies like farming, architecture, and politics certainly continued to evolve. Farming was perhaps the most important, as the new understanding of animal biology caused farmers to develop entirely new farming tools with the help of skilled Medieval artisans; the result was that horses for the first time were used to their full potential. Earlier civilizations had relied on oxen to do their work, but with more sophisticated Medieval equipment, horses which were much stronger became the dominant animal used in farm labor. More advanced systems of crop rotation and sophisticated shared fields that could be worked fairly by an entire village came into use. This maximized the agricultural value of local land, which made previously unusable wilderness suitable for agriculture. It also provided a measure of sustainability for land under cultivation for the next thousand years. The result was that small towns became larger and previously deserted wilderness gave rise to villages expanding the land available for settlement, the population, and the economy.
Art too flourished. The Germanic tribes were master smiths of gold and enamel. They constructed geometric and highly abstract designs on a host of largely practical personal objects and pieces of jewelry. The Sutton Hoo ship burial is one of the most impressive discoveries of these art pieces and shows the highly advanced state of Germanic craftsmanship. Painting thrived as well, especially in the Medieval monasteries. Perhaps the most famous expression of this artwork was the illuminated manuscripts that combined painting and gold leaf into ornately stylized, minutely detailed works of art. An entire monastery might devote decades to the preparation of one complete illuminated manuscript.
Roman architecture is rightly admired the world over; yet before 1100 AD, Roman styles were being adapted, construction techniques were being improved, and ever taller buildings were being erected; Romanesque architecture showed clear stylistic links to the older Roman models, but the improving technology allowed more creativity and more impressive buildings, especially churches. Then in 1140 AD, Medieval builders created their own revolutionary breakthrough: the pointed "Gothic" arch and it's associated "groin vault". These were much more flexible elements that allowed new possibilities in architecture.
Soon after, the flying buttress was developed to address entirely new physics in construction as Medieval European masters dealt with building taller structures than any Roman had ever dreamed. Nor were these techniques lost in a vacuum. Inspired by the same zeal that found its way into Gregorian chant and illuminated manuscripts, these new architectural elements were combined into one of the most inspired designs in world history; the Gothic cathedral: Solid foundations, delicate arches, legions of traceries and sculptural decorations, soaring spires and naves so tall that worshipers inside felt the spiritual presence of the Lord.
Nor were these even the most distinctive features of the Gothic cathedrals; their crowning jewels had nothing to do with their architecture. Medieval Europe developed the most sophisticated stained glass working of any previous or contemporary civilization; the beautifully solid stone and intricate decorations created a dark canvas upon which Medieval artists literally played with light, creating deeply spiritual spaces. Thus, all these new developments in architecture and glass making found their perfect expression when drawn together into a balanced, integrated, awesome whole. Their profound spirituality is the only explanation why even relatively modest towns attempted to raise these dangerous to construct, enormously difficult, enormously expensive monoliths to religion; especially when you consider that cathedrals took so long to build that no one who began the job of building or paying for it would ever see the work even half finished. Yet despite the cost, cathedrals of the Medieval Era now dot hundreds of locations throughout Europe.
The cathedrals even became the home of religious schools called cathedral schools or universities - the modern institutions of higher education comes directly from these unlikely religious origins. In fact, throughout the Medieval period, priests were important not only because of the religious benefits they brought to a shrewd ruler; they received the most advanced education on the continent. This was deeply at odds with the Renaissance perception because the Renaissance Era church was deeply at odds with the new scholars who wrote the histories. However, priests trained in all the arts of learning - including reading and writing - which were necessary to ensure the livelihood of a continent spanning institution like the Catholic Church. Their education was a key reason that the church became so critical to the new Germanic rulers, because priests had the administrative skills necessary run the political bureaucracy.
So although the forms of education changed significantly, the church was the preserver of education and learning. As a minor point, it should also be noted that the church did teach a number of things which Renaissance scholars never truly gave them credit for. The church taught logic along the Greek model and even some rhetoric, though certainly not to the extent traditional among the Greeks and Romans. Literature too was practiced extensively, so passionately in fact that most of the old books of Ancient literature were scraped clean for reuse. (Ancient and Medieval books were written on parchment which was a specially prepared form of tough thin leather, and the top layers could be scraped off eliminating most of the original writing and allowing the parchment to be reused. Ink soaks through parchment and the dim remnants of the letters could still be made out but it was usable. In fact, a number of Ancient texts were saved by later historians who recovered the original text from between the letters of the Medieval texts written on top of them.) As you can imagine the destruction of thousands of Ancient texts was one more thing that did not sit well with men dedicated to learning.
Renaissance scholars did not give much credit to their Medieval counterparts for preserving these techniques because they considered the products of their work ridiculous. While deeply important to Medieval scholars, the treatises they wrote to demonstrate logic involved religious minutiae that ranged from the tedious to the ridiculous; one of the greatest questions of the period which spawned a flood of treatises was how many angels could dance on the head of pin. Similarly, while literature flourished, 95% of the output were a uniquely Medieval genre, saints lives. One strike against these works is that they were fairly universally boring, meant to instruct in proper Christian saintly behavior rather than to entertain. The second strike against them is that they were almost universally plagiarized word for word from books on the lives of other saints. Since God was one, and the trinity was one, the logic went that all saints were also one. So it was not considered accurate to speak of the "lives of the saints" but the "life of the saints". Therefore, when constructing the "spiritual truth" of a new saint's life, most of the material was copied out of other saints lives. Having studied some of these works, I can sympathize with the feelings of the Renaissance scholars, yet the church did preserve logic and a thriving literary tradition which were things that scholars of the Renaissance would embrace and make their own.