This is a rich question, and I can only address Western literature as that's what I know best. Beyond the obvious changes in language and culture over the centuries, the general differences between ancient and modern Western literature can be teased out by considering how human consciousness has changed over time. This change has everything to do with the efficiencies we've created so that we have what's called "leisure time"; time to gaze at our navels and think about our thinking.
This idea -- not a new one -- struck me during a college course on ancient Greek literature, where this shift is most clearly visible. The ancient Greek heroes speak about motivating forces as separate entities that don't belong to their personal consciousness. Over time, their dialog goes from something like "Aphrodite charmed me..." to "The heart within me spoke..." The gods became embodied in humanity through our development of self-consciousness by having time to ask What is that voice in my head? Where did that idea come from? In literature, human motivation is probably the most important raw material. This shift from gods to humans figures monumentally in the development of literature over time.
In the most general sense, we have gone from writing stories of being subject to fate to writing stories about will. The fated stories still have their charm because they have entered the realm of archetypes in the collective human consciousness, but the stories of humans exercising their will upon their environment are what enchant us now.
The smaller differences between ancient and modern literature are hidden in shifts in language, which are often driven by cultural attitudes, which in turn are driven by whoever is perceived as holding power.
Prior to the invention of the printing press, the people's "literature" arose from an oral tradition of stories set to song/poetic form so they could be easily memorized. A few, such as the epic Beowulf, were transcribed and survived to our time. Power was held by few in the secular community and the churches. "Common people" didn't read or write and depended on their local clergy to deliver the word of God.
After the printing press was invented, and the Bible was published, things got interesting; some took it on a very destructive world tour that is still going on today, and they have used it to marginalize people who don't fit the social mold of the day. Others have used it for liberation -- if you can read the word of God yourself, why do you need a holy man to interpret it for you, or why would you give up your secular life to a monastic order to be considered worthy of receiving the word of God? Like a gun, scripture can be used to hurt or harm.
With the printing press and increased distribution of knowledge, particularly in this digital age, exponentially more people have been empowered to make their thoughts publicly known, further spurring the development of human consciousness with a freer exchange of ideas. The literature has shifted from bigger, more basic human drive issues of survival and ascendency to power, to the very gray and intricate situations in which we now find
Explanation:
