John Cassian on the Four-Fold Meaning of Scripture
A fifth century Father, John Cassian (c. 360–435), penned a poetic rhyme to reflect an interpretive pattern. Later Medieval figures, such as Nicholas of Lyra, picks up this common pattern too.
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.