Medieval approaches to biblican interpretation
were led by Fathers of the Church
like Saints Augustine
, and Pope Gregory I
Augustine's work On Christian Doctrine is an introduction to how to understand and teach scripture. Its main points are understanding the difference between things in their own right and things as symbols for other things or ideas, as this is useful in understanding the deeper meaning behind scriptural passages. He also mentions understanding science, mathematics, etc. for the purpose of understanding references to them in Scripture.
Augustine has also written an important commentary on the Psalms (whose influence on his writing can be seen in The Confessions) in which he takes a non-literal approach to interpretation. It was Erasmus who said it is more profitable to read a single verse of a Psalm spiritually than to read the whole Psalter literally.
Pope Gregory I's work Morals on Job applied much of the earlier ideas of Augustine and others to the Book of Job, exploring the text on three levels beyond the literal: the moral, allegorial, and anagogical.
The medieval authors also addressed the problem with finding various levels of interpretation: how to prevent readers from gathering any meaning whatsoever.
Medieval biblical exegesis was expecially concerned with the prefiguring of the Gospel in the Old Testament (for example the story of Jonah as prefiguring Baptism and Resurrection), and explaining problematic texts. The Song of Songs is an example because it is a romantic (sexual even) nuptial hymn, and medieval writers looked to find in it meaning about the Virgin Mary, the Saints, and the relationship of Christ to the Church his Bride. If the Song of Songs were simply taken literally, its inclusion in the Canon of Scripture would be difficult to justify, and it would never be read in liturgy for fear of scandal!