I have translated 63 of Catullus poems, and it seems to me that, in all of the translations I have seen, the ethical dative is translated just like a dative of possession. Can anyone give me a specific definition of the ethical dative and its function within a sentence?
Allen and Greenough, A New Latin Grammar, page 247:
The Dative of the Personal Pronouns is used to show a certain interest felt by the person indicated. [Footnote: Compare “I’ll rhyme you so eight years together.” – As You Like It, iii. 2.]
This construction is called the Ethical Dative. [Footnote: Dativus ethicus.] It is really a faded variety of the Dative of Reference.
quid mihi Celsus agit (Hor. Ep. i. 3. 15), pray what is Celsus doing?
suo sibi servit patri (Plaut. Capt. 5), he serves his own father.
at tibi repente venit mihi Caninius (Fam. ix. 2), but, look you, of a sudden comes to me Caninius.
hem tibi talentum argenti (Pl. Truc. 60), hark ye, a talent of silver.
quid tibi vis, what would you have (what do you wish for yourself)?
There appears to be a bit of overlap with the dative of possession; “suo sibi servit patri” differs from plain old “servit patri suo” only in that “sibi” emphasizes that it is his own father. But most of these examples only the person, not any possession, is emphasized. Compare the following idiomatic English renditions:
quid Celsus agit, what is Celsus doing?
quid mihi Celsus agit, I demand to know what Celsus is doing!
hem talentum argenti, wow, a talent of silver!
hem tibi talentum argenti, would you look at that! A talent of silver!
quid vis, what do you want?
quid tibi vis, what do YOU want?
I guess that naughty old Catullus was just ignoring the distinction between person and possession! 
David McClamrock
I think A&G’s definition is too vague. What how is a “certain interest” defined grammatically. Does this comprise both possession and interest. I have looked through countless sources and cannot find an adequate definition. The one thing I have seen, though, is that grammar texts are always sure to state that the dative of the possessor must be used with sum or some other copulative. Look at this line from Catullus
roseis ut huic labellis sonitus citus abiit,
63.74
“the swift sound went away from this one’s rosy lips”
How can you possibly translate this not as a possessive?
“the swift sound went away from the lips for this one”
There is no idea of advantage in this sentence, and no reason to emphasize that they Attis’ lips as opposed to anyone else’s; rather, it seems to me that Catullus is using “huic” as an equivalent to the genitive.
Well, it’s not an ethical dative at least, unless A&G are totally wrong about the ethical dative. If it’s equivalent to the genitive and doesn’t emphasize whose lips they are, then my best guess is that Catullus is flippantly breaking the rule that the dative of possession must go with “sum or some other copulative.” As for why he did it . . . surely your guess is better than mine. 
David McClamrock
The definition IS vague - but I’m afraid that you aren’t going to find a better explanation. The nature of the usage is that it can accomodate a variety of purposes.
quid mihi Celsus agit - emphasizes the speaker’s interest in the question
suo sibi servit patri - emphasizes the subject’s dedication (perhaps?) or possession
at tibi repente venit mihi Caninius (Fam. ix. 2) - draws the listener’s attention to something
hem tibi talentum argenti (Pl. Truc. 60) - emphasizes the surprise that the listener (and, of course, the speaker) ought to feel (by the way, “Well, would you look at that!” is a great idiomatic rendering in English!)
quid tibi vis - emphasizes the desires of the speaker, in contrast to (say) the person who just spoke (but it’s hard to be precise outside of context)
What how is a “certain interest” defined grammatically. Does this comprise both possession and interest. I have looked through countless sources and cannot find an adequate definition.
Given the range of interpretive options, you will probably fail to find a definition that satifies you. I think this is because the ethical dative isn’t REALLY a grammatical function but rather a contextual one - it frames the content of the sentence according to the situation, emphasizing the speaker (mihi), the listener (tibi), or the subject (huic, illi, ei, sibi, etc).
By the way, vir litterarum, I’d love to see more examples of this so-called ethical dative used possessively. Have you kept a list? I’ll try to keep an eye out for them in my reading of Virgil (of course, a much different author). It might be helpful to compare notes.
-David
[several slight errors corrected]
I never had that much of a problem when I translated the first six books of the Aeneid. Catullus’ usage of the dative in Poem 63 seems to not fit any of the rules. I will show another one from the same poem.
mihi ianuae frequentes, mihi limina tepida,
mihi floridis corollis redimita domus erat,
linquendum ubi esset orto mihi Sole cubiculum.
63.65-67
"my doors used to be busy, my thresholds warm, my house had been crowned for me with flowery garlands, when my room ought to have been left behind by me, with the sun having risen.
Within these three lines are three distinct usages of the dative case. The first one is the dative of the possessor with an understood sunt in the first two clauses; the second is the ethical dative beginning the second line which, again, I have trouble fitting into the sentence as you can see from my translation; the third is the dative of agent with the gerundive. I want so badly just to say that the mihi is being used as a possessive for domus, but every source that I have seen explicity states this construction is only used with copulatives, But Catullus here seems to be using mihi as a possessive with both the understood sunt and the “redimita erat.” Having read these lines, I am starting to believe that when Catullus uses the ethical dative, he is not trying to speak of possession but merely trying to point out to the reader who the statement is referring to. I know this is a fine distinction, and I would like to hear your input on it. What I am trying to say is that the use of mihi in that second line merely is showing that the subject of the sentence is not “a house” but " a house of Attis." Whereas a possessive would show that there is some type of possession involved, this ethical dative merely wishes to specify that the sentence is referring only to Attis. What do you think?
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In lieu of useful comments, I’ve attached several translations I snagged from the web. You may have seen these, or may not have seen them. The point is, they all effectively translate the second dubious “mihi” as a possessive (except the 3rd translation, which puts the “my” on “bed” (=bedroom?) instead of “head.”
the twin doors had been crowded for me, and my
house had been wreathed with flowering garlands whenever I
had to leave my bedroom because the sun had risen.
http://www.negenborn.net/catullus/text2/e63.htm
mine were the crowded doorways, mine the warm thresholds,
mine the flowery garlands to deck my house
when I was to leave my chamber at sunrise.
http://www.vroma.org/~hwalker/VRomaCatullus/063.html
There were crowds round my door, my fans slept on the doorstep;
There were flowers all over the house
When I left my bed at sunrise.
http://www.aztriad.com/catullus.html (C.H. Sisson, who also translated the Aeneid, though not entirely lauded with the highest paeans of praise)
Our doors were crowded, the doorstep warm with friends,
Our whole house was cloaked with flowering garlands.
Only when sun was up had I to leave my chamber room.
http://community.middlebury.edu/~harris/Translations/Catullus.html (by William Harris - some interesting translations here; some are not at all literal, e.g. Catullus VI (q.v.! mihi maxime placet)
The first one is the dative of the possessor with an understood sunt in the first two clauses;
I presume you mean erant - since you translate this as “used to be.”
I want so badly just to say that the mihi is being used as a possessive for domus, but every source that I have seen explicity states this construction is only used with copulatives, But Catullus here seems to be using mihi as a possessive with both the understood sunt and the “redimita erat.”
Perhaps Catullus is bending the rigid rules of Classical Latin in order to maintain the anaphora of “mihi ianuae… mihi limina… mihi…”? It seems that, because of the parallelism at work here, this is rather an exceptional case than a normal one, even within the unusual domain of the ethical dative.
Aside from that, your analysis seems plausible to me. Perhaps, as you say, Catullus is using the ethical dative simply to indicate the person that the house has to do with, almost as if he said “the house that is connected, whether in a direct, propietary sense, or merely in the most tenuous of fashions, to Attis.” Without, of course, the verbiage. But seriously, the ethical dative might be an approximation for the possessive pronoun, since it connects a person to a thing in a vague way that still implies possession.
If I find any weird quasi-possessive ethical datives in the Georgics, I’ll post them here.
-David
Thanks for the translations. I fully agree with your analysis. I thought there would be a note on this in Merrill’s commentary, but there is not. It just seems to me that Catullus uses the dative merely to specify with whom his thought is connected. In one of the instances, I mentioned, he is only trying to show the audience that the sound going away from the rosy lips is all referring to Attis as opposed to anyone else. When I enter college, I think I will write a paper on this ambiguous usage of the dative. The only part of Greenough that possibly helps to clear up this issue is its introduction to the dative case in which states that some people argue that the case is essentially locative in function. Catullus’ usage seems to be indicating an almost abstract motion towards the personal pronoun.