Deus Caritas

If you surmised that the pope's encyclical, which was notable among other things for making the case for the essential unity of the different kinds of loves, could have had its roots in St. Augustine, you were correct.  But I could not place the specific passage until just now when I ran across it in City of God.  Does the following have a familiar ring to it?

When a man's resolve is to love God, and to love his neighbour as himself, not according to man's standards but according to God's, he is undoubtedly said to be a man of good will, because of this love.  This attitude is more commonly called 'charity' (caritas) in holy Scripture; but it appears in the same sacred writings under the appellation 'love' (amor).  For instance, when the Apostle is giving instructions about the choice of a man to rule God's people, he says that such a man should be a lover (amator) of the good.  And when the Lord himself had asked the apostle Peter, 'Are you more fond (diligis) of me than those?' Peter replied 'Lord, you know that I love (amo) you.'  Then the Lord repeated his question, asking, not whether Peter loved him, but whether he was fond of him; and Peter again replied, 'Lord, you know that I love you.'  However, when Jesus asked for the third time, he himself said, 'Do you love me?' instead of, 'Are you fond of me?'  And the evangelist goes on, 'Peter was grieved because  the Lord said to him, for the third time: "Do you love me?"' Whereas in fact it was not the third time; the Lord said, 'Do you love me?' only once, but the had twice asked, 'Are you fond of me?'  From this we infer that when the Lord said, 'Are you fond of me?' he meant precisely the same as when he asked, 'Do you love me?'  Peter, in contrast, did not change the word used to express the same meaning, when he replied the third time, 'Lord, you know everything.  You know that I love you.'

The reason why I thought I should mention this is that qute a number of people imagine that fondness and charity are something different from love.  They say, in fact, that 'fondness' is to be taken in a good sense, 'love' in a bad sense.  It is, however, well established that this was not the usage even of authors of secular literature.  But the philospohers will have to decide whether they make this distinction, and on what principle.  Certainly their books are sufficient evidence of the high value they place on love, when it is concerned with good things and directed towards God himself.  My task, however, was to make the point that the Scriptures of our religion, whose authority we rank above all other writings, do not distinguish between 'love' and 'fondness' or 'charity'.  For I have shown that 'love' also is used in a good sense.
-- St. Augustine, De Civitate Dei, Book XIV, Chapter 7

From the same chapter, on the goodness of rightly ordered eros (i.e. "desire," cupidity):

And so a rightly directed will is love in a good sense and a perverted will is love in a bad sense.  Therefore a love which strains after the possession of the loved object is desire; and the love which possesses and enjoys that object is joy.  The love that shuns what it opposes it is fear, while the love that feels that opposition when it happens is grief.  Consequently, these feelings are bad if the love is bad, and good if the love is good.  Let me prove this statement from Scripture   The Apostle 'desires to depart and to be with Christ' [a number of other examples follow --ed.].  All the same, it is the established usage that when we use 'desire' (cupiditas or concupiscientia) without specifying its object, it can only be understood in a bad sense.

Notes on language: It has been said that just as fleas, as the poem goes, "have smaller fleas to bite'em/and those fleas have smaller fleas, and so ad infinitum," so Latinists have smaller Latinists to pick at their work.  For the following passage to make more sense to you, I would suggest that you switch the places of the English words "love" and "fondness" for each other.  But I have quoted the translation (Penguin Classics Edition translated by Henry Bettenson) unaltered because it is his and not mine.  My issue is with the way diligere and amare are translated.  I think that the translator thinks of these words in a different sense than I think of them (and the way you might, and the way the editor of my Latin dictionary does), because in the above passage, "fondness" is supposed to be the higher, more disinterested, more perfect one, while "love" is supposed to be the lower, more self-interested one, whereas I would think of it as being the other way around (refer to the Latin words if I have made this too confusing).

Diligo, diligere, dilexi, dilectus is the word used in John 3:16: Sic dilexit Deus mundum - God so loved the world.  It is related to the English word "diligent," and if you think about it, it is an excellent word to use for self-sacrificing love.  Think of someone who is diligent in his studies.  His friends might be saying, come on, let's go to the bar, or let's go watch Lost or 24 or whatever, and he may want very much to do these things, but if doing well in that class means that he has to use that time to study, even if it's a hard choice, then that's what he'll do.  Or a mother who is diligent in caring for her newborn - if her baby needs her she'll get up in the middle of the night to attend to the child no matter how much she may want to sleep. 

If you look at a Greek NT, you'll see that the word that diligere is translating in this passage is the verb form of the noun agape - which is translated caritas, but in Latin there is no verb version of caritas, so I presume that is why diligere is used instead.   Amo, amare, amavi, amatus is the one that if you look it up in the dictionary has "to like" or "be fond of" among the definitions.  It is used here to translate the verb form of phila which means love (think Philadelphia) also but has different connotations - it wouldn't be used for a divine, supernatural love, but for the natural affection between two men, like brothers.   There are books you might read for a more thorough elaboration, such as C.S. Lewis' The Four Loves (I haven't read it but I imagine it's pretty informative).

Do you remember one of Pope Benedict's first homilies as pope (perhaps Pope John Paul's funeral)?   The Gospel for the day was this very passage, and he talked about what it meant that these two different words were used, which he mentioned is not evident in many modern-language translations.