It's often mistakenly believed that medieval universities were mostly seminaries. And at least in our tradition lawyers are advocates, trained to take either side of an argument and make as good a case for it as they can.
The sort of writing that attempts to persuade may be a valid (or at least inevitable) form, but it's historically inaccurate to call it an essay. Trying To understand what a real essay is, we have to reach back into history again, though this time not so far. One can't have quite as little foresight as a river.
To Michel de Montaigne, who in 1580 published a book of what he called "essais." He was doing something quite different from what lawyers do, and the difference is embodied in the name. I always know generally what I want to write about.
These earlier civilizations were so much more sophisticated that for the next several centuries the main work of European scholars, in almost every field, was to assimilate what they knew.
During this period the study of ancient texts acquired great prestige. As European scholarship gained momentum it became less and less important; by 1350 someone who wanted to learn about science could find better teachers than Aristotle in his own era. In the 19th century the study of ancient texts was still the backbone of the curriculum.