Essays are protected, I believe. Usually essays are your own thoughts in your own words about a certain subject or work. I'm trying to remember what the legal documents said about the percentage of directly lifted text to the addition of original analysis and thought. I think it was close to 80/20 concerning the lexicon book overall. That's way over the guidelines concerning fair use for scholarly work.

The guidelines for fair use can be googled. The legal documents concerning this lawsuit are published and viewed freely online as well.