Explanation I use in comments on student papers:
Your discussion switches inconsistently between present and past tense.
It is conventional in critical essays to use the so-called “literary present” when analyzing a work, even if the author or work is from the past. (The work is still present for us to look at.) So, for example, when discussing Milton’s Paradise Lost, critics usually stay with a consistent present tense–”Milton writes in Book 12 that . . . ,” “Paradise Lost reveals to us . . . ,” “Milton’s images demonstrate that . . . ,” “Milton writes in blank verse, and Wordsworth uses the same form. . . .” (Not “Milton wrote”; note also the use of present tense for both Milton and Wordsworth even though they lived in different times).
The exception is when your discussion deliberately places the analysis of a work in the context of a historical event or period (or compares writers as historical figures). For example, if you are writing about Milton’s work in relation to the history of England, then the following is correct: “Milton wrote his epic poem when England was just coming out of crisis.” You would stay with the historical past tense so long as you were working in the historical mode. When you then turn to close-reading the work, you would then switch to literary present.
(Note: in complex discussions when a critic oscillates between analysis and historical explanation, there are gray areas where it is difficult to know which tense to use. Just aim for what feels like consistency.)
