From
Dante’s letter to Can Grande della Scala,
translated by James Marchand, http://www.english.udel.edu/dean/cangrand.html.
7. For me be able to present what I am going to say, you
must know that the sense of this work is not simple, rather it may be called
polysemantic, that is, of many senses; the first sense is that which comes from
the letter, the second is that of that which is signified by the letter. And
the first is called the literal, the second allegorical or moral or anagogical.
Which method of treatment, that it may be clearer, can be considered through
these words: "When Israel went out of Egypt, the house of Jacob from a
barbarous people, Judea was made his sanctuary, Israel his dominion"
(Douay-Rheims, Ps. 113.1-2). If we look at it from the letter alone it means to
us the exit of the Children of Israel from Egypt at the time of Moses; if from
allegory, it means for us our redemption done by Christ; if from the moral
sense, it means to us the conversion of the soul from the struggle and misery
of sin to the status of grace; if from the anagogical, it means the leave
taking of the blessed soul from the slavery of this corruption to the freedom
of eternal glory. And though these mystical senses are called by various names,
in general all can be called allegorical, because they are different from the
literal or the historical. Now, allegory comes from Greek alleon, which in
Latin means other or different.
8. Now that we have seen this, it is obvious that the
subject around which the two senses turn must be twofold. And therefore it is
to be determined about the subject of this work when it is taken literally,
then about the subject when it is understood allegorically. The subject of the
whole work, taken only from a literal standpoint, is simply the status of the
soul after death, taken simply. The movement of the whole work turns from it
and around it. If the work is taken allegorically, however, the subject is man,
either gaining or losing merit through his freedom of will, subject to the
justice of being rewarded or punished.
From Thomas Aquinas, Summa
Theologica, I.i.10 (1260s-70s). (Translation at http://www.newadvent.org/summa/100110.htm.)
The author of Holy Writ is God, in whose power it is to signify His meaning, not by words only (as man also can do), but also by things themselves. So, whereas in every other science things are signified by words, this science has the property, that the things signified by the words have themselves also a signification. Therefore that first signification whereby words signify things belongs to the first sense, the historical or literal. That signification whereby things signified by words have themselves also a signification is called the spiritual sense, which is based on the literal, and presupposes it. Now this spiritual sense has a threefold division. For as the Apostle says (Hebrews 10:1) the Old Law is a figure of the New Law, and Dionysius says (Coel. Hier. i) "the New Law itself is a figure of future glory." Again, in the New Law, whatever our Head has done is a type of what we ought to do. Therefore, so far as the things of the Old Law signify the things of the New Law, there is the allegorical sense; so far as the things done in Christ, or so far as the things which signify Christ, are types of what we ought to do, there is the moral sense. But so far as they signify what relates to eternal glory, there is the anagogical sense. Since the literal sense is that which the author intends, and since the author of Holy Writ is God, Who by one act comprehends all things by His intellect, it is not unfitting, as Augustine says (Confess. xii), if, even according to the literal sense, one word in Holy Writ should have several senses.
From Augustine, On Christian Doctrine (translations from D.W. Robertson, Jr., Preface to Chaucer 25):
“Scripture teaches nothing but charity, nor condemns anything except cupidity (or lust), and in this way shapes the lives of men” (3.10.15)
“I call ‘charity’ the motion of the soul toward the enjoyment of God for his own sake, and the enjoyment of one's self and one's neighbor for the sake of God; but ‘cupidty’ is a motion of the soul toward the enjoyment of one's self, one's neighbor, or any corporeal thing for the sake of something other than God.” (3.10.16)
From Augustine, Confessions (NA, 1116):
“So You have ordained and so it is: that every disorder of the soul is its own punishment”.