So what the heck is mimesis in the first place? A lot of thinkers have thrown this word around, so it's good to make my usage clear. The simple answer is that mimesis means "imitation" or "representation."
My use of mimesis is all about representation: how has literature represented the reality of life? To me, mimesis relates to daily, lived existence, and to how the Western canon (at least a lot of it) produced reality for the reader. Remember: the subtitle to my book is The Representation of Reality in Western Literature. So what I want to ask is: to what degree did Western authors represent or imitate the worlds about which they wrote? Boom. That's mimesis.
We're not talking about flowers and chocolates. We're not even talking about Wordsworth and Byron and other early 19th-century poets. We're talking about Romance languages, baby.
Romance Philology includes the study of Latin and heaps of languages that developed from it during the Middle Ages, like Spanish, French, Italian, Portuguese, and Romanian. English is not included—it's a Germanic language, though it does has tons of words that come from Latin and French.
Philology is the study of how the languages formed and have changed, and of how that relates to literature. So a Romance philologist is somehow who studies Romance languages and literature, their contexts, and the ways they have changed over time.
Let's start with historicism—which is, basically, interest in historical context. We historicists are crazy about setting the scene for events. If we're studying a Shakespeare play, we want to know all about Elizabethan theaters and Elizabethan politics. We try to look at situations on their own terms and not see them as universal events with grandiose symbolism.
Just as I'm into close reading (which is looking at small passages of text in order to understand the greater work), I like to take nice, long looks at individual situations in texts and find out what makes them unique. Bonus points if it's a realist text, since these texts try to represent the conditions of life in the most historically faithful way.
Now, here's where the aesthetic part comes in: I look at these individual moments and situations through the lens of aesthetics—specifically literature. I look at literary art to try to figure out what Joe Schmo is up to on a given day because I think literature can tell us a lot about what reality was like at a given time. A regular historicist might look at newspapers or political documents to get a feel for history, but I look at literature.