Traditionally, the Church has identified four levels of meaning or 'senses' of Scripture: the literal sense and three spiritual senses - the allegorical, the moral, and the anagogical senses. Aquinas explains these in his Summa Theologiae, in Article 10 of Question 1 in the Prima Pars:
Whether in Holy Scripture a word may have several senses?
Point: How confusing would that be? We'd all get confused and believe untrue things about God, and surely the Bible can't lead us into untruth, right?
On the other hand: Gregory the Great says that "Holy Writ, by the manner of its speech transcends every science, because in one and the same sentence, while it describes a fact, it reveals a mystery."
Reply: The author of Scripture is God, who is able to signify meaning with things as well as words, so some of the things described by the words of the Bible themselves point to other meanings. The historical or literal sense of Scripture is the obvious meaning, the things that the words directly point to, so when the Bible talks about rocks, the literal sense of its words are rocks: you know, those hard, stony things. But then there's also a threefold spiritual sense. When things in the Old Law signify things in the New Law, that's the allegorical sense: so when the Old Testament describes Moses hitting the rock and water flowing from it, that text refers literally to an actual rock, and allegorically to Jesus, from whom living water flows. Then when things symbolise what we ought to do, they are to be read in the moral sense: so when Jesus challenges anyone without sin to throw rocks at the woman caught in adultery, the moral or tropological sense is that we ought not to judge because we are sinful too. Finally, the anagogical sense is when the words of the Bible refer to our eternal glory, so when the Israelite prophets refer to the restoration of Jerusalem, the literal meaning is the actual city of Jerusalem, but the anagogical sense is the Kingdom of God.
Aquinas says that these four senses don't need to confuse us, because they're all based on the literal sense, and there isn't anything in the Bible which is there in the spiritual sense but not in the literal sense.
This division of the meaning of Scripture into several senses is pretty common from very early in the Church right up to the Reformation, after which it fell a bit out of favour, and everyone got very excited about reading the Bible literally or pulling it apart with 'scientific' historical criticism. It's been becoming more popular again recently, though, and however much people might talk about sticking to the literal sense of Scripture, it's rare to find anyone who completely avoids the other senses. I think we do several of these senses a lot in the charismatic church, particularly when reading the Old Testament or prophesying, but often people aren't that aware of what they're doing when they give, say, an allegorical reading of Scripture. I think it's worth being aware of because how we read the Bible matters, and how we understand what we're doing when we read the Bible affects both how we read it and how we assess other peoples' readings of it.
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