The letter teaches events
Allegory what you should believe
Tropology what you should do
Anagogy where you should aim.
Meanings of texts, for some ancient and medieval interpreters, are bound up in this four-fold pattern. Thus, meaning is not solely bound to a literal interpretation, but also extends into allegorical, moral, and tropological patterns of interpretation.
Quotations found in C. Ocker, “Biblical Interpretation in the Middle Ages,” in Dictionary of Major Biblical Interpreters, ed. Donald K. McKim (Downers Grove, IVP Academic, 2007), 18.