Laudator Temporis Acti

Edward Kennard Rand, Founders of the Middle Ages (Cambridge: Harvard University Press, 1928; rpt. New York: Dover Press, 1957), p. 86:

St. Thomas Aquinas and Dante give what looks like a final and scientific statement about allegory, with the four varieties of meaning that might attend a verse of scripture or a poet's verse—the sensus literalis, that is, the obvious or historical meaning of the words; sensus moralis, their application to human character; sensus allegoricus or mysticus, the prophecy of the Gospels in some passage of the Old Testament; and the sensus anagogicus, which revealed somethg about man's existence in the life to come.

When I read, I seldom get beyond the sensus literalis, the literal meaning of the words, which is often not at all obvious, at least to me. See, for example, Donald J. Greene, "'Pictures in the Mind': Johnson and Imagery," in Johnson, Boswell and Their Circle: Essays Presented to Lawrence Fitzroy Powell in Honour of His Eighty-Fourth Birthday (Oxford: Clarendon Press, 1965), pp. 137-158 (at 141):

The modern reader can, of course, miss the subtler points in Johnson's imagery. Sometimes this is because time has obscured references that were vivid to Johnson and his audience. The point of Johnson's quip about the Scotch, 'Droves of them would come up [to London], and attest anything for the honour of Scotland' is lost (even though Boswell tries to help by italicizing the key word) when we fail to see, what Johnson's contemporaries did, the dense herds of Scottish cattle regularly driven down the dusty roads of northern England to Smithfield. The metaphor in Johnson's protest about Boswell's habit of trying to stimulate controversy between Johnson and others is now virtually dead—'It is very uncivil to pit two people against one another.' But again Boswell's italics indicate that it could call up a vivid picture when cock-fighting was still a popular sport.

David West, The Imagery and Poetry of Lucretius (Edinburgh: Edinburgh University Press, 1969), is especially good at this kind of analysis.

Related post: Fossil Poetry.