Dante and the word "Anagogical"

In part seven of "Letter to Can Grande della Scala," Dante discusses how there is not just a single sense in the work, but several senses (polysemous). While I understood this word, especially after he followed it up with a short definition, I had a bit of trouble with "anagogical." I looked it up in the OED and found that other words that are related to this are mystical and spiritual. I liked the short definition I found online that stated an "idealistic striving of the unconscious." After looking this word up, I felt that I better understood what Dante was trying to say. He felt that there was a literal way to look at a letter, but also a second anagogical way. Though he also used the words moral and allegorical, they didn't really help me understand what he meant by anagogical. No worries now, however :)